Green space around the university campus is of paramount importance for emotional and psychological restorations in students. Positive emotions in students can be aroused when immersed in green space and naturalness. However, to what extent can perceived naturalness influence students' positive emotion remains unclear, especially in the context of COVID-19 countermeasures. This study, therefore, attempts to investigate in-depth the nature and strength of the relationships between students' positive emotion and their perceived naturalness, place attachment, and landscape preference, which are potentially varying across universities in different social and environmental contexts and different restrictions policies regarding the COVID-19 pandemic. A course of questionnaire-based surveys was administered on two university campuses in Heilongjiang and Hunan Provinces, China, resulting in 474 effective samples. Structural equation modeling was used to explore the hypothetical conceptual framework of latent variables and the indicators. The findings indicate that the higher students' perceived naturalness results in greater positive emotion. Students' perceived naturalness in green spaces of campus has a positive effect on their place attachment and landscape preference. Moreover, the difference between mediate effects of place attachment and landscape preference were addressed, which verifies the contextual influences. As a public health issue, the global pandemic of COVID-19 poses a serious threat to the built environment and human health , 3. In CThe psycho-evolutionary theory suggests that people's emotions can be positively affected by observing the natural environment . As the However, although green spaces have similar characteristics to a certain extent, it is not reasonable to regard the perceived naturalness of the CGSs in different areas as the same as students' restorations . ConceptAt present, university students from different regions of China have experienced different periods of lockdown. The perception of naturalness, emotions, and the level of stress are affected by the regulations depending on the varying intensity of COVID-19 spreads . ResearcThis study aimed to explore the hypothetical effects of place attachment and landscape preference in the relationship between the perceived naturalness of CGSs and university students' positive emotions under the restriction policies and regulations to control the spread of the COVID-19 pandemic. We comparatively investigated the hypotheses considering the social and environmental differences between two universities in Hunan and Heilongjiang provinces, China. Due to the different epidemiological conditions during the COVID-19 period in China, these two universities imposed control regulations with different intensities. The findings are expected to provide up-to-date contextual insights into the relationship between perceived naturalness and positive emotion and to systematically understand the mechanism that perceived naturalness in CGSs evokes the student's positive emotion. Furthermore, the implications are expected to help the planning and management of university green spaces for improving the mental health and well-being of university students.Perceived naturalness refers to the proximity of the landscape to the perceived natural state , while eLiterature studies on the COVID-19 pandemic revealed that natural deprivation associated with lockdown leads to restriction of physical activity and experience of negative emotions such as anxiety and depression among university students , 35. On Place attachment, as place identification and place dependence, is a positive emotional connection established between people and places through memory and exposure to the environment , 40 is aAs an emotional bond between people and important places, students' place attachment is linked to their emotions . StudentLandscape preference is formed through the interaction between people and the natural environment . The envCGSs provided natural spaces to meet university students' landscape preferences, which contributed to generating positive emotions among students in the university , 55. MorSeveral studies showed that social and cultural contexts influence the form and function of green spaces, which affects individuals' perceptions of the environment , 58. In The exogenous variables used for constructing latent variables are listed in The field surveys were conducted on two campuses, namely campus of university A (UA) in Changsha of Hunan Province and the campus of university B (UB) in Harbin of Heilongjiang Province, in China. According to the Köppen climate classification, Changsha is classified as Cfa and characterized by mild temperate climate and fully humid climate with hot summers, while Harbin is classified as Dwa and characterized by snow, dry winters, and hot summers . The locOn the campus of UA, the green space is scattered and includes lawns, trees, and a river. There are many geese in the river. The outdoor activity area is crowded. Minor noises are caused by the green space under construction. Each green space has a unique character. The green areas in UB consist of large lawns, distinct flora, and fauna. A rich variety of plants is observed. The river flows through the campus. There are good opportunities for outdoor activities, good natural quality, and strong attraction. The scenes of the two campuses are shown in A questionnaire was developed for the survey with five parts. The first part is regard to collecting information on students' socio-demographic characteristics, including gender, age, education level, and monthly living expense. The second part is used to acquire students' perceived naturalness in the form of a self-rated naturalness scale (SRNS) . The thiFrom February to April 2021, students were randomly invited to join the surveys in the two selected universities. All participants voluntarily took part in our surveys, and the collected questionnaire forms are anonymous for privacy issues. Before answering the questionnaire, respondents were informed of the purpose of the questionnaire and asked to recall their emotional states during their routine activities in the CGSs over the past 2 weeks. Finally, of the 539 possible eligible questionnaires, 474 completed questionnaires passed the validity check .Structural equation modeling (SEM) is a popular method for data analysis that has been widely used in many fields, such as psychology, sociology, and education. Unlike other modeling approaches, SEM integrates a measurement model and structural model, which can directly respond to the relationship between latent and observed variables, as well as the relationship between latent variables .The equation of the measured model is as follows:X denotes the vector consisting of measured variables of the ith independent latent variables, Y denotes the vector of measured variables of dependent latent variable; Λxi and Λy are matrices of factor loadings for X and Y, respectively; δ and ε are measurement errors of independent and dependent latent variables, respectively; and ξ is a vector of latent independent variables and η is a vector of latent dependent variables. The variances and covariances among the measurement errors of measured independent variables in X are contained in Ωδ, and the variances and covariances among the measurement errors for the measured dependent variables are included in Ωε.where The regression equation of the structural model is as follows:B is the regression coefficient matrix regarding the latent dependent variables; Γ is the regression coefficient matrix relating latent independent variables; and ζ is the vector of the error term in the structural model equation that contains the equation prediction errors. The variances and covariances among the latent independent variables are included in a matrix Φ, and the variances and covariances among latent dependent prediction errors are contained in a matrix Ψ.where To estimate the SEM model, it is assumed in this study that the outcomes were continuous when the random variables follow a normal distribution. Maximum likelihood (ML) was used to figure out the estimation of the model regarding all parameters simultaneously. ML yields an estimate that seeks to maximize the likelihood that the measured data are consistent with the implied model, which is given as :xi, Λy, Ωδ, Ωε, B, Γ, Φ, and Ψ; tr is the trace of the matrix; S is the covariance matrix observed in the data; p is the number of indicators for exogenous latent variables in the model; and q is the number of indicators for the endogenous latent variables in the model. The loadings and coefficients are obtained when the difference between the covariance matrix elements of measured data and the covariance matrix elements implied by the model is minimized.where The sociodemographic characteristics of respondents are shown in ≥ 0.9, indicating an acceptable fit to the model (≥ 0.9 indicates that the model is acceptable (The Tucker–Lewis index (TLI) is widely used to model linear mean and covariance structures. The value of The TLI also ranges between 0 and 1, with results he model . The comceptable . Root Meceptable . As showAs shown in The direct mediate effect of place attachment is not verified in the models of both universities. This result is inconsistent with recent research, which concluded that place attachment was beneficial to students' positive emotions and mental health . One of Compared to UB, the joint mediating role of place attachment and landscape preference was not validated at UA. This is mainly due to the absence of a link between students' landscape preferences and positive emotions. People's landscape preferences are heterogeneous and dynamic and can be influenced by temporal, spatial, and personal factors . As for This study aimed at understanding the importance of perceived naturalness in university campus greenspaces for improving students' positive emotions, especially after the controlling regulations of the COVID-19 pandemic. The questionnaire-based surveys have been undertaken in two universities in Heilongjiang and Hunan Provinces to collect data on students' positive emotions, perceived naturalness, place attachment, and landscape preference regarding CGSs in different social and environmental contexts.A comparison of SEM results of the sample groups from the two different universities indicates that perceived naturalness, place attachment, and landscape preference influence positive emotion in different manners. The findings suggest that students' perceived naturalness of the CGSs can directly influence their positive emotions. Meanwhile, students' place attachment and landscape preference can be facilitated by the perceived naturalness of the CGSs, ultimately leading to more positive emotions.With the improvement of campus environments of Chinese universities in the last two decades, students can experience a more natural and better-designed campus environment than in other urban spaces . NeverthThe raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Academic Ethics Committee of School of Architecture and Art, Central South University. The patients/participants provided their written informed consent to participate in this study.SL, YJ, JL, and ZL carried out investigation and made data curation. SL, YJ, JL, and YP made formal analysis. SL and YJ wrote the original draft preparation. YP, WL, and TF reviewed, revised, and edited the manuscript. All authors contributed to the article and approved the submitted version.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.


To evaluate the agreement among instruments of the quantitative evaluation of hard palate.This cross-sectional study was performed with a sample of 30 children aged 6 to 11 from Santa Maria, Southern Brazil. The instruments for palate measurements evaluated were: digital caliper, used directly in the oral cavity and in plaster casts, Korkhaus tridimensional bow, used directly in the oral cavity and in plaster casts, and Dolphin Imaging Software used for measurements in cone-beam computed tomography (CBCT). The agreement among different instruments was evaluated using the Intraclass Correlation Coefficient (ICC).The means of all transversal dimensions obtained by cone-beam computed tomography were lower than those of the other instruments - the agreement values in the width between the canines and in the width between the first molars were lower when comparing the cone-beam computed tomography and the other instruments. In the width between the first and second premolars, all comparisons showed acceptable agreement values. Good concordance values were obtained when comparing the palate depth at the second premolar region when using a bow divider inside the oral cavity and in the cast.Most instruments presented satisfactory agreement in the measurements related to the transverse plane of the hard palate. However, when the vertical plane was evaluated, only the bow divider applied to both cast and oral cavity presented ideal agreement. Its anatomy is closely related to orofacial functional activities. Therefore, its morphological analysis is characterized as an important part of the clinical evaluation of speech therapists working in Orofacial Motricity, and of dentists who work in Orthodontics. When their dimensions are altered, it can be predicted that oral functions and/or breathing will be impaired, to a greater or lesser degree,3 and the Korkhaus tridimensional bow divider-6 are among the most frequently used instruments found in the literature. They may be applied directly inside the oral cavity,6 or in plaster models,3,5. The Caliper is a commonly used measuring instrument because it provides objective data in the evaluation of the hard palate and is advantageous because it is a simple, non-invasive, painless, and risk-free technique,8. The three-dimensional Korkhaus bow divider is useful because it allows a three-dimensional assessment of the structures, however, it requires training for its use and is more complex to manage.Subjective criteria are still the most used methods for morphological assessment of the hard palate in clinical practice. However, there are studies using different quantitative methods for the measurement of the hard palate. The caliper-11, or cone-beam computed tomography (CBTC) images. Digital plaster models do not require physical storage and are also advantageous because they allow instant accessibility of information, as well as the ability to perform diagnostic configurations in a simple and electronically accurate manner. Relation to CBTC, it contains low doses of radiation, a quick scanning time, and a high accuracy in the images obtained, also allowing the diagnosis through digital measurements,12. Furthermore, there are even instruments designed specifically for the measurement of hard palate dimensions in plaster casts found in the literature.In addition, it is also possible to use softwares for the measurement of digital palate modelsKnowledge about anthropometric measures contributes to the establishment of therapeutic conduct, as well as to the subsequent follow-up. Thus, given the different methods for hard palate measurement found in the literature, it is essential to investigate whether these instruments provide comparable results. Thus, the aim of this study is to verify the agreement among the instruments of quantitative evaluation of the vertical and transverse dimensions of the hard palate. The conceptual hypothesis was that different instruments yield similar and compatible results since all of them provide dimensions in millimeters.The present study was registered and approved by the Ethics Committee in research on human beings of the Center of Health Sciences of the Federal University of Santa Maria under number 220.0.243.000-8. Only subjects who agreed to their participation, and whose parents or legal guardians signed Free and Informed Consent Forms were included.This study is nested within a larger epidemiological survey carried out in 2015 in the city of Santa Maria, Southern Brazil. For the umbrella study, children were selected through a two-stage cluster process. The first stage consisted of schools (n = 9), followed by the inclusion of children enrolled in them. Schools were considered according to the sample weight and were distributed in the 8 administrative regions of the city. Subjects for this cross-sectional study were 30 children aged 6 to 11 years, with the full permanent upper-molar eruption and normal occlusion or Class I malocclusion. Subjects who presented evident cognitive syndromes or limitations, craniofacial malformation, or who had undergone orthodontic treatment were excluded.Sample size calculation was made based on a pilot study. Pearson correlation test was used between hard palate measures obtained by different instruments. Based on the smaller “r” value (0.197) and a total number of 16 subjects, it was verified that 25 would be the minimum number of subjects to be included in the study.Assessments of the hard palate measurements were performed by two gold standard examiners in the area. One of the examiners (L.C.B.) performed all Caliper measurements within the oral cavity and in models and Korkhaus three-dimensional bow - within the oral cavity in models; and the other examiner (A.C.R.C.) performed all measurements through the CBCT. For the calibration process, hard palate measures were repeated after 7 days in 20% of the sample randomly selected, in order to assess intra-examiner reproducibility by means of the Intraclass Correlation Coefficient (ICC). The general ICC values ranged from 0.23-0.99. The specific values of ICC for each measure of the calibration process are described in  of canine, premolar (or deciduous molar) and permanent molar teeth as reference , used directly in the oral cavity and in plaster casts , used directly in the oral cavity and in plaster casts  could only be obtained in the plaster models because of the method adopted. A stainless steel orthodontic wire was cut so that its length would be equal to the transverse measure (width), and fixed with utility wax between the reference points at the level of each of the reference teeth . The depth was measured with the caliper rod, corresponding to the perpendicular measure from the median palatine line to the orthodontic wire uniting the region of each of the relevant teeth . The diaWithin a week after the plaster models were made and the measures taken within the oral cavity, each subject underwent a CBCT scan , which allowed cranium and facial scanning for future computerized reconstruction. The tridimensional images (DICOM) captured were exported to Dolphin Imaging Software and a previously trained examiner performed the measurements in coronal plane ..Data were analyzed by software SPSS 20.0 . The agreement study among different instruments for the different measurements of the hard palate was undertaken by calculation of the ICC. Reliable values must be superior to 0.70The sample consisted of 30 children evaluated for measurements of the hard palate. Regarding transverse measures , smallerRegarding vertical measures , only on-6, the agreement among different methods has not been explored yet.This study was undertaken as a comparison between agreements for different methods that may be used in the measurement of the hard palate, seeking to assess whether different methods may provide comparable results, given that there is as yet no gold standard in the literature for this type of evaluation. Our findings partially confirm the conceptual hypothesis, since the measurements were only comparable for transverse measurements. Although some previous studies have undertaken the comparison of hard palate measurements among different variables, such as sex, age group, ethnicity, and oral habits. The analysis of intra-examiner reproducibility may lead to the inference that frontal hard palate depth measurements with bow divider and caliper may not be reliable, and does not support the internal validity of the studies. On the other hand, when the objective is to study the vertical dimensions of the frontal hard palate, the use of CBCT scans seems to be more appropriate.Regarding the intra-examiner reproducibility of the methods under evaluation in this study, the values obtained were within acceptable limits for all width dimensions. On the other hand, in the analysis of vertical measures, agreement values were progressively smaller toward the frontal region of the mouth. At canine level, the bow divider yielded values much below acceptable levels. With the use of the caliper for depth measurement in models, agreements values at canine and first premolar levels were higher than those obtained with the bow divider, but were still beneath acceptable levels. The low agreement values between test and retest depth measurements in the frontal hard palate region may be explained by the difficulty in finding the ideal support point for the rods of the instruments in a region with a more curvilinear anatomy, thus reinforcing the difficulty in identifying this tissue in conventional exams. When CBCT scans were compared to the other instruments, it was verified that canine width presented concordance levels below the expected in comparison with bow divider , and with caliper within the oral cavity. One possible explanation is that the low agreement levels found between CBCT scan and the other instruments is related to the identification of the reference points used in this study. The coronal plane is not influenced by soft tissues, whereas, in the clinical hard palate measurement with caliper and bow divider, the gingival margin must be taken as reference point, which may justify the low agreement among methods.In the analysis of the results for transverse measurements, the means of the transverse dimensions obtained by CBCT scans were smaller than those obtained by bow divider and caliper both within the oral cavity and in models. One possible explanation for this would be that it is difficult to detect soft tissues by conventional CBCT scans. The literature presents one study proposing a way to eliminate the overlap of structures with a view to make the visualization of position and thickness of gingival tissue easier.On the other hand, for width measurements between first and second premolars, all comparisons among methods presented acceptable agreement levels, including comparison with CBCT scan. It may be suggested that, at premolar or deciduous molar levels, the reference point used in CBCT scans is closer to the one clinically identified in the gingival margin. At premolar level, there is higher stability regarding the thickness of the epithelium covering the palate, as well as regarding the position of the gingival marginRegarding the width between first molars, agreement values were below expectation in the comparison between CBCT scan and caliper within the oral cavity. This difference may be explained not only by the impossibility to locate the gingival margin in tomography planes, but also by the difficulty in locating the apical gingival margin at first molar level in the oral cavity, due to the more distal position of these teeth in relation to the others considered in this study. This hypothesis is corroborated by the higher agreement value found for the comparison between CT scan measurements with those taken by caliper in model., and to the differences between in diameter the bow divider’s vertical rod and the caliper’s vertical rod area,8.Regarding vertical measures, most agreement values among instruments were below expectation. The only acceptable agreement value was depth obtained at second premolar level, when compared to the value obtained for the use of bow divider both within the oral cavity and in the model. It may be observed from this that the hard palate depth measurement instruments under consideration in this study may yield differing results. It is believed that the difficulty in obtaining compatible values among frontal hard palate depth measurement instruments is due to the variability of palatine roughness in the region of the incisive papilla, which displays results digitally. On the other hand, it was verified that most comparisons among vertical measures for the various instruments presented low agreement values, thus disallowing this study’s hypothesis. Acceptable agreement values were observed only at second premolar levels in comparison between vertical measures obtained with bow divider both within the oral cavity and in the model.From the comparative analysis of the different instruments under consideration in this study for hard palate width measurement, it was verified that most of the comparisons (87.5%) presented agreement values within acceptable levels, the highest being those of vertical measures at premolar levels. Among the instruments in question, the caliper may be the best choice for measurements both within the oral cavity and in plaster models, as it is a low-cost, precise and easy-to-handle toolThis study has some limitations. The analysis undertaken in this study does not allow inference of which instrument would be most suitable for hard palate depth measurement. It is believed that some anatomic peculiarities, such as the inherent structural concavity, and different epithelium features and degrees of thickness may have contributed to the lack of equivalence among measures by different instruments. It is necessary to take into account the specificities of the instruments used to obtain the depth dimensions at the level of each of the teeth that were considered. Different means were found in the comparison among the different methods, and it was observed that depth values taken by bow divider tend to be undervalued in relation to those obtained by other instruments.The use of the bow divider for depth measurement at canine level both within the oral cavity and in model and of the caliper for depth measurement at canine and first premolar levels yielded non-reproducible measures. This indicates that caution is necessary in relation to these instruments for the assessment of the frontal region of the hard palate depth. More research is necessary on the subject in order to improve palatine vertical measures, since the agreement values obtained in the present study were below the ideal.Our findings showed that most hard palate measurement instruments present satisfactory agreement for transverse values. However, for vertical dimensions, a low agreement was verified among most instruments.


As major and serious complications after hematopoietic stem cell transplantation (HSCT), graft-versus-host disease (GVHD) and sepsis are the chief causes of low survival rates as well as mortality and for HSCT recipients. Although the overall treatment outcomes of HSCT have improved significantly in recent years, there is still an increased incidence rate of complications and mortality after transplantation. In the immediate past, with a deeper understanding of oxidative stress, more and more shreds of evidence have shown that it is closely related to transplantation-related sepsis. However, there is currently a precious little research on the interaction between oxidative stress and complications after HSCT, and the major mechanism has not yet been clarified. The objective of this study was to assess the internal connection between and potential mechanisms as well as visualized the scientometrics results of all important literature related to the topic. Through exhaustive scientometrics analysis, we searched and carefully screened 286 related publications from the Web of Science Core Collection (WoSCC) with “((HSCT) OR (hematopoietic stem cell transplantation)) AND (oxidative stress)” as the search strategy. Then, detailed visualization of the overall information analysis was made by scientific and rigorous bibliometrics software or website. Next, we analyzed retrieved articles extensively and then 59 publications that are relevant to this topic were selected for nuanced analysis and summary. The assessment of these studies proved the validity of the interaction between oxidative stress and complications after HSCT objectively and directly. Hematopoietic stem cell transplantation (HSCT) refers to a treatment method that pretreats the transplant recipient through high-dose radiotherapy, chemotherapy, or other immunosuppressants, clears the tumor cells and abnormal clonal cells in the recipient, blocks the pathogenesis, and then transfuses autologous or allogeneic hematopoietic stem cells to the recipient so that the recipient can reestablish normal hematopoietic and immune functions in the body, so as to achieve the purpose of treatment –3. HematSepsis is a clinical syndrome caused by excessive inflammation after infection, including immune abnormalities, coagulation abnormalities, and systemic multiple organ dysfunction . The earScientometrics is a novel discipline that mainly focuses on the research of the quantitative angle of the scientific process as an important communication system . ScientoTherefore, the purpose of this study is to conduct real-time scientometrics analysis of existing relevant studies and present the latest trend of the interaction between oxidative stress in HSCT and its related sepsis, so as to find the current research hot spots, lay a theoretical foundation for subsequent clinical research, and further provide the relevant research foundation for the application of evidence-based medicine and translational medicine, with the aim of providing new insights for OS- and HSCT-related complications.A publication search was conducted in the Web of Science Core Collection (WoSCC) of the Web of Science database on July 19, 2022. Firstly, we used ((HSCT) OR (hematopoietic stem cell transplantation)) (All Fields) AND (oxidative stress) (All Fields) as the search strategy, and then, 286 publications were obtained. Next, we read all the search results extensively and excluded 227 publications that were not closely related to postoperative complications. Finally, 59 publications were obtained. Then, we exported all the full records and cited references with the data style of TXT.https://bibliometric.com/) were used to conduct the following analysis and visualizations based on the scientometrics and bibliometric principle:Cluster analysis and hot time presentation of all keywords from 286 publications based on the cooccurrence relationshipThe timeline visualization of the keywords from the 59 screened publicationsCoauthor relationship between countries and organizations and their relative number of publicationsStatistical analysis of basic information of journals with the largest number of publicationsThe cluster analysis of the cited journals is based on the cocitation relationshipVisualization of citation relationship and cluster analysis between journals of the screened publications and their referencesIn the process of data processing, VOSviewer (version 1.6.17) and Citespace (version 6.1.R2) and an online website of bibliometrics . It is used for cooperation between countries (Here, we continue to conduct an in-depth analysis of the cooperation relationship and research situation among the units of 59 selected publications so as to find out the research units with deep research in this field. The online website of bibliometrics (ountries . Among tountries . We can Firstly, we statistically processed the journals with more screened publications and visually presented the total number of publications, the total number of citations, and the impact factor . The numAnd then, the visualization of citation relationship and cluster analysis between journals have been made . The lefOne of the most common complications after hematopoietic stem cell transplantation is infection and its related sepsis because as long as large doses of radiotherapy and chemotherapy are carried out, there is a period of bone marrow suppression, which will cause patients to cause a variety of infections due to granulocyte deficiency, including bacterial infection, fungal infection, and viral infection. If poorly controlled, it is easy to lead to sepsis, which will lead to a worse prognosis and irretrievable outcome.The oxidative stress after hematopoietic stem cell transplantation is in a delicate balance, and its specific mechanism remains to be elucidated. Based on this, we conducted a literature search and a novel scientometrics research on this hot topic. The initial search was based on the topic of hematopoietic stem cell transplantation and oxidative stress. For the retrieved publications, we conducted cluster analysis on all the keywords and mapped the cooccurrence network. The purpose was to preliminarily get the relationship between the research hot spots under the relevant subjects, so as to select the hot information or topics related to them. In this research, in addition to “oxidative stress” as the search term, the words “progenitor cells”, “self-renewal”, “iron overload”, and so on appear more frequently. In addition, there are some words that have appeared in recent years although they are less frequent, such as diagnostic impact, ineffectiveness, indoleamine 2,3-dioxygenase, and labile plasma iron. These words may become new hot spots in future applications or research. Readers can choose the keywords they are interested in or further explore the keywords that have a strong cooccurrence relationship with them and have a relatively recent appearance.Blood, Bone Marrow Translation, and Biology of Blood and Marrow Transplantation have a high number of publications and citations and have considerable influence factors; readers can selectively read the publications from these journals based on the information when making inquiries. We also conducted cluster analysis based on the cocitation relationship for the source journals of the cited references. We believe that the cocitation relationship can effectively reflect the relevance and theme consistency between journals. For example, Blood, Frontiers in Immunology, and Nature Reviews Endocrinology appear in the same cluster. Perhaps this relationship can be used to select journals and help readers to contribute. In addition, we also presented the citation relationship between the publication source journals and their reference source journals and also perform simple clustering based on this. The specific situation has been marked with different labels. Meanwhile, an intensive reading part of recently published literatures was shown in Next, in order to obtain more accurate results, we excluded studies unrelated to complications or prognosis, and only 59 publications were retained. Timeline view is used here to present the clustering results of keywords and their cooccurrence relationships. We also divided the keywords into 13 clusters, and each cluster is labeled with a tag. This is a summary of the keywords in this cluster. Through such tags, readers can quickly identify the hot spots they are interested in. For example, the tag of the first cluster is T cell, and the keywords related to immune cells or immunity are mainly presented in this cluster. In addition, hot spots and cooccurrence networks are also shown in the figure. The cooperation relationship between the countries/organizations of the screened publications is shown in the study. The observation of visual images can help readers choose which countries or organizations have more in-depth research in this field. In-depth analyses of the journals from which the publications are sourced were done. We first conducted a multidimensional statistical analysis of the data of the journals from which the selected publications came, including the statistics of the total number of publications, the number of citations of all publications, and the presentation of the value of different journals. We found that journals such as As a negative effect of free radicals in the body, the process of oxidative stress is often and considered to be an important factor leading to diseases . In partIn this study, we conducted a novel scientometrics analysis on the publications on the topic of oxidative stress and HSCT. As far as keywords, countries, research institutions, and journals, we present their potential relationships, including cooccurrence relationships, coauthor relationships, and cocited relationships, in a variety of analytical ways. The multidimensional visual analysis helps readers to select the hot spot information they are interested in according to the chart, so as to carry out further research, clarify the mechanism, and optimize the clinical diagnosis and treatment measures.


Automated and autonomous vehicles are in an intensive development phase. It is a phase that requires a lot of modelling and experimental research. Experimental research into these vehicles is in its initial state. There is a lack of findings and standardized recommendations for the organization and creation of research scenarios. There are also many difficulties in creating research scenarios. The main difficulties are the large number of systems for simultaneous checking. Additionally, the vehicles have a very complicated structure. A review of current publications allowed for systematization of the research scenarios of vehicles and their components as well as the measurement systems used. These include perception systems, automated response to threats, and critical situations in the area of road safety. The scenarios analyzed ensure that the planned research tasks can be carried out, including the investigation of systems that enable autonomous driving. This study uses passenger cars equipped with highly sophisticated sensor systems and localization devices. Perception systems are the necessary equipment during the conducted study. They provide recognition of the environment, mainly through vision sensors (cameras) and lidars. The research tasks include autonomous driving along a detected road lane on a curvilinear track. The effective maintenance of the vehicle in this lane is assessed. The location used in the study is a set of specialized research tracks on which stationary or moving obstacles are often placed. Currently, there are a large number of publications on autonomous vehicles. Most of these papers, along with their included research and discussions, deal with technological aspects. The dominant topics are vehicle control, avoiding road obstacles, and sending information about the current situation of the vehicle and possible threats. This is happening because these vehicles are in a phase of intensive development. A very important stage of development work is model and experimental research.The test vehicles, often conventionally referred to as autonomous in many publications, perform strictly planned tasks during research. Thus, they operate as automated vehicles. In this paper the abbreviation AV will be used, which should be considered as an automated or autonomous vehicle. According to the SAE J3016 standard , autonomHowever, experimental research related to AVs is in an initial state. This is confirmed by a small number of studies of complete control systems for such cars. For example, there are studies that analyze environment perception systems and the vehicle control is investigated separately. Research is still at the stage of gathering knowledge about the performance of different systems under different conditions. Research plans are visible and adapted to the current cognitive needs of the research organizer. This situation is the result of a lack of recommendations and standardized guidelines for the scenarios used in such studies. There is a big problem and binding arrangements  for the organization of safe AV testing in road traffic is sorely needed . Particu-the number of systems to be checked at the same time is significant and the vehicles have a very complex structure;-the number of places where conducting research is possible is limited;-the trajectory of the tested vehicle may deviate significantly from the planned trajectory;-the legal regulation of AVs’ participation in traffic is inconsistent and unclear in different countries.The main difficulties that are faced during the creation of research scenarios with a planned course  can be summarized as follows:A complication in the organization of the tests also arises from the fact that, in traffic, all the vehicle’s systems will be operating simultaneously or in a sequence that is difficult to plan .-the results of model tests and computer simulations in which the behavior of the vehicle in virtual space can be safely observed ;-the results of analysis focusing on cooperation between computer models and the systems of a real vehicle (technologies: HIL );-research results of complete vehicle actuators in combination with road tests and the simulation environment ;-results of the validation of the human–machine interface through the interaction between the driver and the autonomous vehicle (technologies: DIL );-research results of the vehicle at the proving grounds .The development of scenarios for experimental research related to road traffic can be based on the results of previous studies (available in significant numbers), namely:There is a general consensus that the scenarios of such research should result from the observation of road traffic and drivers’ behavior ,11,12.Currently, there are significantly more simulation studies than experimental studies. In ,14, the -aim of the research;-test vehicle (platforms) data and the method of their preparation and configuration;-the use of the environment  in which the research will be conducted;-a set of elements and additional objects (complementary) which are required to be included in the research;-initial conditions and the planned course of the study (test sequence);-measuring equipment, its tasks, and method of use;-the quantities necessary to measure, the level of accuracy of the measurements, and the method of evaluation of the results;-safety procedures.The above-described research and all other experimental research related to AVs has been conducted according to specific scenarios. The experimental research scenario requires a lot of information to be established:Similar findings are included in scenarios in current normative research regulations, e.g., SAE , Euro NCThe aim of the article is to present the main information about AV research scenarios, and the study tasks undertaken in this area, in an orderly manner. The collected material aims to systematize the information that will facilitate the planning, preparation, and execution of experimental AV research. The developed material will allow test preparation time to be shortened, the repetition of already performed research to be avoided, and the number of wrong decisions made at this stage to be reduced . The systematization of available information on normative and non-normative scenarios will facilitate their analysis and the assessment of their applicability when planning AV research.-research tasks that currently dominate;-elements to be included in the AV research scenario;-which normative documents are useful for organizing research;-what measuring and recording equipment is necessary.The material gathered in the article will help identify the following:This paper presents the currently used normative scenarios of experimental AV research. Scenarios used by various research centers will be characterized, in which the plan and course is adapted to the current needs of researchers (nonnormative scenarios). Attention will also be paid to the technological aspects of the research scenarios, as well as the measurement systems and sensors used in the research.On the basis of the literature analysis, a hierarchical scheme of information necessary for the creation of AV research scenarios has been built. The layout of this scheme is shown in There is a lack of publications focused on the preparation and organization of AV research. In publications containing the results of experimental studies, the authors mainly focus on the results of these studies, and information about their preparation and scenario is limited. This additionally justifies the need to gather and systematize knowledge in this area. During the preparation of the article, our own database of scientific publications about AV research was used. The database was created over many years of research carried out at the Research Network Łukasiewicz—Automotive Industry Institute in Warsaw on the improvement of AVs.The collection of research material for the article was based on the usage of scientific publications databases such as Springer, Science Direct, MDPI, Taylor & Francis, IEEE Xplore, ResearchGate, and SAE International. Moreover, online resources from many organizations were analyzed separately, including Euro NCAP, NHTSA, ISO, EU, UNECE, and IIHS. The result of tagging topics of interest and research areas was also a set of keywords. This was the starting point for the search of publications in the databases. Selected articles were categorized in three areas . These areas are the main content of the article.Experimental AV research considers many multidisciplinary issues related to the road traffic control process. One of the most frequently studied issues is the problem of object detection by the environment perception system. An example of such research conducted by the Łukasiewicz Research Network—Automotive Industry Institute in Warsaw is shown in A large amount of the papers published in this area discuss the problem of road edge and lane detection by AVs ,27,28. RAnother research problem is avoiding obstacles on the road. Planning an avoidance maneuver requires information from the perception system about the position and dimensions of the obstacle. There is a separate need to define the area in which the AV can continue driving after passing the obstacle . Based on this, the decision-making system generates a trajectory for further driving (path planning). Usually, these are trajectories safely avoid obstacles in road traffic .Maintaining the planned path strongly depends on the curvature of the path and driving velocity. These factors influence the lateral force values , which causes sideslip and lateral skidding of the tires. The result is a deviation of the real trajectory from the planned path. This deviation can be measured as shown in This is exemplified by the planned path The figures show the influence of driving velocities on driving trajectory deviations from the planned path. The lateral forces  increase with increases in driving velocity on the curvilinear path, which causes sideslip and lateral skidding of the tires. As a result, an increase in the lateral deviation -recognition of the road situation;-planning a collision-free path;-current assessment of the real trajectory in relation to the planned path and making the necessary corrections.AV’s contribution to road traffic is based on many activities. These include:-navigation and digital maps of the driving area;-location of the vehicle in relation to the road infrastructure;-environment perception to recognize the situation around the vehicle.Path planning is based on:The problem of planning and maintaining a planned path is often the aim of experimental research or is part of other research in which the planned path is an indirect factor.The primary task during AV movement is performed by the perception system. The result should be at least the detection of the road lane edge or its centerline and an estimate of the relative position of the car in that lane. This is the dominant problem of experimental research in the aspect described here.Experimental AV research scenarios found in the literature have a certain set of features. These often depend on the aim of the research. The main features of the AV research scenarios, in terms of self-driving and the effectiveness of lane-keeping by the vehicle, are summarized in -effectiveness of road line (lane boundary) detection;-the planning of a safe path for avoiding a slower moving vehicle.The next scenario concerns research into avoiding suddenly appearing obstacles . Thus, t−EU ;−UNECE ,38,39;−ISO ,41,42;−Euro NCAP ,22,43;−NHTSA ,45,46;−SAE ,47;−IIHS ,49.Normative AV test scenarios and procedures are used to test finished products and automation systems, e.g., for homologation. An example of a type of system for which normative testing is carried out is ADAS. Driver assistance systems include FCW, AEB, LKA, or ESP. ADAS are maximum level 2 solutions according to SAE ,36. TheyNormative scenarios allow for repeated testing of entire vehicles and their systems. Unified procedures, equipment, and methods of evaluation of test results make it possible to compare the various solutions used in AVs. This makes it easier to decide on appropriate directions of development for active safety systems in vehicles. A structured overview of normative testing scenarios is presented in Normative test scenarios are focused on the testing of finished systems in AVs. These are most often certification, homologation, and ranking tests (these tests are not of a cognitive nature). The analysis of normative test scenarios shows that the largest part of studies is currently carried out for driver warning, emergency braking, and lane keeping systems. The effectiveness of these systems is assessed in terms of vehicle response to the detected threat (only the effect of the system’s reaction is assessed). This may include the threat signals for the driver or the effectiveness of an automatic defensive maneuver. Normative scenarios are mostly carried out on test tracks/proving grounds with the necessary infrastructure. Selected scenarios enable tests to be conducted on public roads. In these cases, critical situations are ignored and AV control is not implemented. The analyzed normative scenarios indicate that AV tests are currently focused on critical situations in road traffic. This is the basis for building nonnormative research scenarios. These nonnormative scenarios should focus on the cognitive aspects of autonomous vehicle operation. The reasons for the AV’s reaction to the threat should also be assessed .−AV path planning ,34, wher−following the previous vehicle, e.g., as part of the movement within two circles ;−road line detection and traffic lane detection ,27,70, w−○driving with high velocities on highways ,32;○driving on a racing track on a wet and dry surface and different strategies of AV path planning .AV lane keeping:−emergency braking before an obstacle ,71,72, w−avoiding a suddenly appearing obstacle in a critical situation where it is not possible to stop the AV ,72;−○car detection ,73,74 an○pedestrian detection ,21,69;○bicyclist/motorcyclist detection ,73,74.2D object detection, localization, and tracking:−○car detection ,75,77;○pedestrian detection ,24,78;○bicyclist/motorcyclist detection ,25,73;○cone detection ;○detection of walls, trees, bushes, and poles ;○detection and tracking of unknown objects .3D object detection on the road ,76 usingNonnormative test scenarios are created to conduct experimental research related to the development and analysis of the performance of AV systems. Therefore, these are scientific pieces of research of a different basis than the normative test scenarios described in the previous section. These scenarios are focused on the cognitive aspect of experimental research. Such scenarios are also needed during component/system research, e.g., object detection by the perception system ,68,69, pThe analyzed nonnormative research scenarios indicate that currently single AV systems (components) are the main directions of development within experimental research. Few publications discuss scenarios where a complete AV system is analyzed in terms of its control. Some focused on critical situations and these are conducted on tracks. Algorithms such as lane keeping, braking, or obstacle avoidance are being investigated. The number of these publications is growing, but it is still small in relation to the research of single AV systems (components). This can be influenced by the cost of conducting research into complete AV systems. They are also characterized by the complexity of preparation for the research scenario and a very large number of variants. The issue of perception systems focused on object detection and line/edge detection on the road is widely researched. A significant number of research scenarios for these systems are evident. They are often carried out in road traffic because they do not reduce the level of safety for other road users. These studies are focused on calm driving without the risk of critical situations.The organization of research according to specific scenarios requires meeting the technical requirements contained therein. Technical aspects in the research scenarios include the characteristics of the research environment and the characteristics and parameters of the vehicle. The relevant issues in this area will be presented below.−buses ;−trucks ;−microcars (single person) ;−go-karts ;−research platforms (autonomous systems carriers) or physical models of the car at a reduced scale ,81.Research according to the described scenarios is usually carried out with the use of passenger cars . The movThe use of reduced-scale car models allows for significant reductions in research costs, the space required for their realization, as well as the risk of possible damages in case of a defective realization of the scenario. It should be noted, however, that conducting research on physical models may not provide complete information on the dynamics of real car motion, and the problem of scaling vehicles is a complex and problematic issue ,83,84.−the proving grounds for testing and validation of AVs in Zalaegerszeg (Hungary) and Immendingen (Germany) ,86;−proving grounds Mcity (Almono (Uber ATG)) and Kcity ,87,88;−proving grounds containing an oval track (such as KATRI—Korea Apparel Testing and Research Institute) ;−tracks used in car racing  ;−fragments of road infrastructure excluded from public traffic which have been specially selected for conducting research according to specific scenarios ;−polygons using an unstructured environment ,91, whicMany countries still do not allow the testing of autonomous vehicles on public roads. Therefore, in addition to limited road fragments, special places are prepared for the realization of experimental research of autonomous cars, such as:The number of public roads where research is allowed is small, but has been increasing recently .The realization of experimental research often requires the use of additional objects. Their presence within the range of the car’s perception system is the basis for the operation of the control system. In road traffic, these include other vehicles, pedestrians, cyclists, or fixed obstacles. If the course of the research is not related to the realization of critical maneuvers, the scenarios depend on the state of road traffic. Research results according to such scenarios are available in ,67,70.Due to limitations surrounding the possibility of conducting research on public roads, it is necessary to conduct research in a closed area. In such an area, real objects  are replaced with various types of dummies, decorations, and physical models. Dummies of pedestrians, children and bicyclists are used in a similar role  and during critical situations (active safety systems). This type of experimental research requires many sensors. These sensors can be divided into sensors for the AV’s perception and control systems, as well as devices recording the results of research (measuring equipment).AV perception systems are an integral part of any control system, regardless of their level of sophistication. Single sensors are used in simple systems ,44,55. MThe sensors of the perception systems are mainly vision sensors (cameras) recording RGB images ,32,70, rRadars are commonly used sensors which provide information about obstacles and vehicle movement parameters. Radars are used for emergency braking systems , active −GPS ,33,74;−GNSS RTK ,75,95;−IMU ,34,95.AVs are equipped with additional sensors for control systems, namely:The GPS/GNSS system enables localization of the vehicle’s position using a satellite signal. This is a very common sensor. It is usually used for global path planning of the AV. The disadvantage is the low accuracy of the localization—usually 1–10 m. An extension of this system is to complement GPS/GNSS with RTK. It is a GPS system that allows precise determination of the position of the vehicle in real time. In addition to the GPS in the car, this kit uses an additional signal from a stationary reference station, which also receives a GPS signal. The reference station sends the data about position correction to the receiver in the car. This increases localization accuracy to approximately 4 cm.The IMU sensor is a device that integrates an accelerometer, gyroscope, and magnetometer. This sensor enables the determination of vehicle acceleration, angular position, and angular velocity. IMU is very often found as a supplement to GPS and GNSS RTK systems.In experimental research, AV cameras are used to detect lines on the road  or durin−radar–camera–GPS fusion ;−radar–camera fusion .The signal from the radar can be used to calculate the object’s motion parameters  ,71,72. RLong-range radars are mainly used for object detection at high driving velocities, with short-range radars used for precise maneuvers at low velocities. Radars are used in braking and obstacle avoidance scenarios , 3D objeLidars create an image of the environment in the form of a point cloud ,44. BaseLidar sensors with a wide horizontal field of view  and a large number of scanning layers  have high scanning resolution with a wide vertical measurement range. Reducing the number of scanning layers while maintaining the vertical measurement range limits the resolution of the sensor (reducing information about the objects). Maintaining high resolution with a lower number of scanning layers can adversely affect the observation of tall objects. Lidars with a narrower horizontal scope of observation are also used in AV research . Additionally, 360 deg sensors allow the entire environment surrounding the AV to be scanned with a single device . The disadvantage of this solution is the lack of information about obstacles in close proximity to the AV due to insufficient vertical measuring range. The use of sensors with a smaller horizontal measuring range requires the installation of several devices around the vehicle to observe the entire environment. This increases the vertical measuring range in areas close to the vehicle. The disadvantage is the high cost of many devices. Increasing the number of scanning layers, resolution, and horizontal measurement range of the sensor/sensors increases the size of the collected files. This may have an adverse effect on the time taken by the AV’s perception system to detect objects.The analysis of the sensors used in the perception and control systems shows that the most commonly used solutions in AVs are based on cameras (2D detection) and lidar sensors (3D detection). Many scenarios use sensory fusion of these two sensors. This enables the elimination of the disadvantages of individual sensors, as well as the extension of the measurement capabilities of the AV’s perception system. Lidars that fully scan the environment around the vehicle are increasingly used. This enables the use of a single sensor on the vehicle. The use of sensors with an increasing number of scanning layers is visible in AV research. In experimental research, radars are mainly used in normative scenarios as the basis for ADAS solutions . Additionally, in ADAS and in nonnormative scenarios, cameras are used to test LKA, LSS, or perception systems which detect lines or road signs. There is a growing number of research results which take into account sensors such as GPS and GNSS RTK, enabling precise determination of the AV’s position . There is increasing research into the impact of AV dynamics and kinematics in terms of its control. For this purpose, IMU sensors are increasingly being used to measure quantities such as acceleration or angular velocity of the vehicle.Experimental AV research uses a wide range of sensors which are necessary for perception and control systems. Verification of the operation of the AV system requires external measuring equipment, which will enable the parallel measurement of selected physical quantities  and other signals. These recorded data are the basis for assessing the performance of AV systems in the considered research scenario.−waveforms related to the movement of the vehicle/obstacle ;−information and warning signals from the AV system interface;−course of the experiment ;−signals related to the vehicle control process.The measuring equipment is only used to record the course of the research and does not affect the decision-making or AV control process. The measuring equipment used depends on the considered research scenario; however, several characteristic areas of measurement can be identified:The measurement of waveforms related to the movement of the vehicle or obstacle for a given scenario is related to the measurement quantities such as the position of objects, driving velocity, acceleration , angular velocity, etc. For this purpose, information transmitted by GPS/GNSS, GNSS RTK, and IMU sensors is used . In scen2, steering wheel angular velocity 1.0 deg/s). These requirements are developed for scenarios related to emergency braking systems, collision warning systems [Normative scenarios specify the range of vehicle dynamics parameters and the obstacle parameters necessary for registration during the tests. Either the sampling frequency  or the accuracy of the measurements is indicated . The normative test scenarios for these systems are described in ,28,43. VCameras are used to record the progress of an experiment. They can record the course of the research inside the vehicle or can be mounted on the AV’s body and record the surroundings of the vehicle. For this, SLR cameras can be used, which can additionally be activated at a defined point in time in order to synchronize data recording ,51 . The measurement equipment used is often characterized by high measurement accuracy, which allows the measured results to be used as a reference for signals from the AV. This mainly applies to nonnormative research scenarios.-normative and unified , which are applicable when testing vehicles and their systems in a repeatable manner ; unification of scenarios will make it possible to compare the different solutions used in AVs;-nonnormative, which were developed in various research centers; their course is adapted to the current needs of researchers. The research is of a cognitive nature and indicates the ways AVs can be improved and developed.Experimental research is carried out according to more and more complex scenarios. The scenario makes it easier to organize and conduct research. It contains a lot of important information, e.g., the aim and scope of research, measurement equipment, and safety procedures. The analyzed scenarios were divided into two groups, which were conventionally named:There are a significant number of scenarios that focus on the research of AV systems. The leading area of research regarding components is perception systems. These systems are dominated by two methods of object detection: 2D and 3D detection. Systems based on vision sensors use single-lens cameras that provide 2D images. On the other hand, systems with stereo cameras provide a spatial image from two lenses. This solution enables 3D observation, typically at distances of up to 30 m. An advantageous but costly solution is to use information from radar and lidar . This arrangement enables the spatial localization of objects and road infrastructure at greater distances than a stereo camera. It makes it easier to detect obstacles and increases the accuracy of object detection, determining their distances to AV and dimensions. Increasingly, at the stage of processing information from sensors, sensory fusion methods (combining information from cameras and lidars) and neural network models are used for object detection (obstacles) in road traffic.AV research has been carried out in dedicated areas of road infrastructure. In such an area, real objects  are often replaced by various types of dummies, targets, and physical models. Their location is described in test scenarios, and the results have an impact on the effectiveness of the AV control process, including obstacle avoidance. This process affects the realization of the planned path and road safety. The AV control system requires current information about the position of the vehicle and the road lane. The investigated scenarios showed that this process is based on the use of information from sensors and systems, such as GPS, GNSS RTK and IMU sensors/systems.-there is a lack of publications reporting experimental research related to AVs;-there is little information that can be obtained about the experimental research scenarios in the analyzed publications;-the lack of many legal regulations in the field of these studies means that a large part of the scenarios should be treated as individual ideas and solutions.The current experience, resulting from the analysis of AV tests, indicates the need for further standardization of research procedures. However, the limitations in the conducted analysis result from several factors:Expanding activities in this area will increase the possibility of comparing and summarizing experimental AV research results, which will create an increasingly complete picture of the behavior of autonomous vehicles in road traffic. The knowledge gathered in this way should significantly improve road safety and set directions for the further development of AVs. Future scenarios should also include the study of necessary changes to road infrastructure to facilitate the operation of AVs. Defining these scenarios should take into account the current capabilities and advancement level of AV systems.This article indicates the currently dominant research tasks and methods of AV research. Another important area of systematized information is lists of standards describing standardized procedures for ADAS systems testing. In addition, an important fragment is the comparison of frequently used AV sensors with the available research topics. This makes it possible to compare the results of research centered on the use of a given sensor model to the results of other works in this field.The designation for AV as used in this work also includes the terms contained in Regulation (EU) 2019/2144 of the European Parliament and of the Council of 27 November 2019 , where a


China is the only country in the world that has not included the Haemophilus influenzae type b (Hib) vaccine in its National Immunization Program, making it more difficult to eliminate Hib-related diseases through Hib vaccination. It is necessary to study parental preferences for Hib vaccination to optimize vaccine promotion strategies in China.This study aimed to investigate Chinese parental preference for five attributes of Hib vaccination, i.e., the place of origin, effectiveness, adverse event, doctors' recommendation, and the price of full vaccination when making a decision to vaccinate their children under 2 years old.A cross-sectional survey was conducted in two cities in Zhejiang Province from November to December in 2020 using a discrete choice experiment (DCE). A mixed logit model was used to estimate participating parents' preference for Hib vaccination attributes included in the DCE. Subgroup analysis and probability analysis were also conducted to capture the heterogeneity and trade-off of parental preference for Hib vaccination.Data from 6,168 observations were included in the analyses. Parents of children are, on average, more likely to voice a positive preference for Hib vaccination. Such attributes of Hib vaccination as effectiveness and doctor's recommendation have a significant positive influence on parents' preference for Hib vaccination, while imported vaccines, adverse events, and the price of full vaccination have a significant negative influence on parents' preference. Parents with different demographic characteristics also existed heterogeneities in preference for Hib vaccination. Parents will make a trade-off on price if the Hib vaccine has a good performance on effectiveness and safety.The study found that, regardless of the place of origin of the Hib vaccine, parents with children under 2 years old prefer to compromise on price if the vaccine has a better effectiveness and safety profile. A proactive recommendation from doctors would strengthen their willingness for Hib vaccination. These findings help aid the development of communication strategies with parents for Hib vaccination in China. Haemophilus influenzae type b (Hib), a gram-negative cocobacillus bacterium, occurs mainly in children under 5 years of age  and is a common cause of morbidity and mortality in this group of children  and is among the four countries with the highest number of Hib-related deaths worldwide . SpecifiThe Changchun Changsheng vaccine incident  that occurred in 2018 has caused Chinese parents to become more concerned about vaccinations, and more and more parents are proactively searching for information about the non-NIP vaccine online to determine whether to get their children vaccinated . WhereasDiscrete choice experiment (DCE), a quantitative attribute-based survey method, is widely used in public health to assess community views and preferences and to measure benefits (utility) , 18. TheIn this study, we aim to look at factors affecting the preferences of parents with children aged under 2 years old for Hib vaccination in Zhejiang Province, and conduct a systematic analysis of parental preferences through subgroup analysis drawing on the theory of DCE. To the best of our knowledge, this study represents the first DCE work to investigate parental preference for Hib vaccination in China. As mentioned above, the background that the Hib vaccine was not included in the Chinese NIP and the increased awareness of parents about vaccination encourages us to explore parent preferences for Hib vaccination based on the current situation, which serves as a stepping stone for future research in Hib vaccination in China. The second objective of our study is to propose several insights and policy advice in terms of effectiveness, adverse events, doctor's recommendations, and place of origin of Hib vaccines based on the results of all analyses, which can provide a reference for adjusting and optimizing Hib vaccine immunization strategies in China in the future.via Wenjuanxing , an online survey company in China between November and December of 2020. Father or mother of children under age 2  was recruited in the observation room after routine vaccination with informed consent, and grandparents and other family members of children were excluded. The sample size was determined according to the equation of c among different attributes in this study was 4, and the number of choice sets t and the number of alternatives in each set a was 8 and 2, respectively. Therefore, the minimum value of N could be estimated as (500 × 4)/(8 × 2) = 125. To ensure that a sufficient number of valid questionnaires are collected, we invited 120 parents in each city  to file the questionnaire. The study was approved by the Chinese Center for Disease Control and Prevention Institutional Review Board (#201944).This study was conducted in two cities of Shaoxing and Wenzhou in Zhejiang, a developed province in the east of China. And then two districts/counties with per capita GDP ranking in the upper and lower quartiles  in 2019 and providing Hib vaccines were selected from each city. Four vaccination clinics were then selected by convenient sampling  in each district/county. Priority is given to vaccination clinics that can supply both domestic and imported Hib vaccines. A total of 16 vaccination clinics were invited to participate in the study. The survey was administered online 0×c(t×a) , where tIn the discrete choice experiment, participants are asked to complete a series of questions, and each of which corresponds to a hypothetical scenario . Each scFollowing methodological guidelines of DCE , we firs2×32×41) and a total of 10,296 possible pair-wise choices , excluding grandparents and other family members, and the whole investigation process was divided into two stages: pre-investigation and formal investigation. To check the comprehensibility, acceptability, and effectiveness of the complete electronic questionnaire, the convenience sampling method was adopted in the pre-investigation stage. A vaccination clinic in Beijing  was selected to carry out the pre-investigation, and the existing problems in the pre-investigation were further modified.In the process of investigation, for each participant, a professional investigator would give one-on-one guidance to each participant to scan the QR code of the electronic questionnaire and fill in it by using mobile phones or other convenient mobile devices. Specifically, the team of investigators was formed by the vaccination clinic itself, and they need to be uniformly trained to be competent for this investigation. Each investigator works on three tasks: First, the significance of the investigation, the DCE questions, and other questions should be explained in detail to each participant. Secondly, before filling in the questionnaire, the investigator should explain the contents of the informed consent, and inform the participants that the questionnaire will be filled out anonymously, and the relevant information will not involve personal privacy and confirm the participants' willingness to participate in this investigation. For participants who agree to participate in this investigation, they should be asked to fill out the questionnaire truthfully. Finally, the investigator should fill in the vaccination clinic code correctly so that the number of completed questionnaires for each clinic can be checked in real-time in the database, and the questionnaire administration time for each participant should be limited to 20–30 min. After the successful completion of the pre-investigation, a formal investigation was carried out in 16 vaccination clinics in Zhejiang Province.i derives from choosing alternative j in choice scenario t can be calculated as follows:We used a most promising state-of-the-art discrete choice model, the mixed logit model , 30, 33,Xijt denotes a vector of observed attributes of alternative j in choice scenario t ; βi represents a vector of individual-specific coefficients that reflect the preferability of the attributes; the multiplication of Xijt and βi represents the fixed utility of participant i choosing alternative j in choice scenario t; εijt denotes a random utility of participant i choosing alternative j in choice scenario t.where Uijt that participant i derives from choosing alternative j in choice scenario t can be calculated as:Among the five designed DCE attributes, the price is coded as a continuous variable and the other four attributes are coded as dummy variables. Thus, the utility ASC_None is an alternative specific constant for choosing not to vaccinate   , and theWe first estimated the main effects mixed logit model to assess parental preferences for the different levels of attributes compared with the reference group. To consider preference heterogeneity, each coefficient was presented as having a mean and a standard deviation, and the mean denotes the overall average preference, and the standard deviation is the individual-specific preference. We also performed subgroup analyses from 4 perspectives to capture differences in Hib vaccination preferences among participants with different characteristics . Results from the main effects mixed logit model was also employed to analyze the percentage change in the probability of choosing that specific alternative compared to the base alternative by changing the level of a given attribute. Initial data obtained from the electronic questionnaires were pre-processed using Python software, and all analyses were performed using Stata 15.A total of 257 parents of children aged 0–2 years old participated in the study. To ensure internal consistency of the data, i.e., the participants filled in the electronic questionnaire rationally, the results of the choice test for all participants in the duplicated choice tasks were examined, and 38 out of all participants failed in the consistency test. The characteristics of participating parents and their children are shown in To determine whether there is a difference in the DCE results based on all samples  and consistent samples, we constructed mixed logit models in these two different datasets, respectively. Both models achieve convergence and their results are reported in p-value < 0.05), suggesting these four attributes were meaningful on parental preference for Hib vaccination  at all levels were significantly different from the reference group , and the remaining four attributes all have unobservable preference heterogeneity. When we examined the coefficient of ASC-None, we found a significant negative influence. The result indicated that parents are, on average, more likely to voice a preference to choose Hib vaccination for their children, regardless of the level presented by the other attributes.The relative preferences of participants for different levels of attributes are important in explaining the experimental results of the DCE. The coefficient of effectiveness with different levels showed that the positive influence of effectiveness with 95% is greater than effectiveness with 85% compared with effectiveness with 75%. Similarly, the coefficient of adverse events with different levels showed that the negative influence of the high adverse event on parental preference for Hib vaccination is greater than the moderate adverse event. Parents also had strong preferences for Hib vaccination for doctor's recommendation and Hib vaccines with low price. Out of all five attributes, the adverse events exist homogeneous preferences , and all results can be found in the Subgroup analyses revealed several heterogeneities in preferences for Hib vaccination across the following perspectives in the –A3. UnliProbability analysis, a simulation method, is also utilized to analyze the percentage change in the probability of choosing that specific alternative compared to the base alternative by changing the level of a given attribute. In relation to the levels of price , which is a high guideline to increase the willingness to vaccinate with Hib vaccine . For theIn this study, the influence of parental attitudes and cognitions on Hib vaccination also is investigated through parental evaluation of individual attributes. We also effectively observe and analyze the trade-offs and decisions made by parents in Hib vaccine attribute changes using DCE according to their repeated choice results in various hypothetical scenarios. It is no denying that this study exists some limitations. Different from other similar studies , 49, we Effectiveness, adverse events, price and doctor's recommendation are significant attributes when parents are making the decision of whether to choose Hib vaccination for their child. Chinese parental preference for Hib vaccination that emphasizes parents are more willing to compromise on price if the vaccine is more effective and safer. And doctors' proactive recommendations for Hib vaccination enhance parental perceptions of the importance of the Hib vaccine. Regardless of the place of origin of Hib vaccines, parents prefer to choose Hib vaccines that have better effectiveness and safety profile and are cheaper for their children. Furthermore, subgroup analysis reveals that parents with different demographic characteristics existed heterogeneities in preference for Hib vaccination. These significant findings will contribute to the development and optimization of future immunization strategies for Hib vaccination in the future in China.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Chinese Center for Disease Control and Prevention Institutional Review Board (#201944). The patients/participants provided their written informed consent to participate in this study.XW and YF contributed equally to the problem of the study, preprocessed data, performed the experiment, significantly to analysis and manuscript preparation, performed the data analyses, and wrote the manuscript. QZ, LY, and MC prepared and wrote ethics application materials, designed the discrete choice experiment questionnaire, and collected data. PL and SLiu helped design the discrete choice experiment questionnaire and helped perform the analysis with constructive discussions. SLi contributed to the problem of the study. ZY and JZ contributed to the problem of the study and revised the manuscript, and provided financial support. All authors contributed to the article and approved the submitted version.This research was funded by the China Medical Board (CMB), grant number 20-379. JZ was funded by a Disciplines Construction Project: Multimorbidity (WH10022022034).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.