A modified CVD method for the synthesis of monolayer MoS2and photoelectric improvement by HfO2passivation.

Molybdenum disulfide (MoS2) is an emerging class of new materials with a wide range of potential practical applications. However, the uncontrollability of monolayer MoS2synthesized by traditional chemical vapor deposition method and the low responsivity of MoS2photodetectors limit its further development in the field of photoelectric detection. To achieve controlled growth of monolayer MoS2and construct MoS2photodetectors with a high responsivity, we propose a novel single crystal growth strategy of high-quality MoS2by controlling the Mo to S vapor ratio near the substrate, and deposit a layer of hafnium oxide (HfO2) on the surface of MoS2to enhance the performance of the pristine metal-semiconductor-metal structure photodetector. At a reverse bias of 8 V, the HfO2passivated MoS2photodetector features an extremely high responsivity of1201AW-1,a response time of around 0.5 s, and a detectivity of7.7×1011Jones.Meanwhile, we deeply investigate the effect of the HfO2layer on the performance of the fabricated MoS2photodetector and propose a physical mechanism to interpret the obtained experiment results. These results might facilitate a better understanding on the performance modulation of the MoS2photodetectors and accelerate the development of MoS2-based optoelectronic devices.

Change in suicidal ideation and associated factors among young adults in Hong Kong from 2018 to 2019: a latent transition analysis.

PURPOSE: Suicide in young adulthood is a vital public health concern. There have been few systematic studies that examined the prevalence and transition of suicidal ideation classes in young adults and the factors associated with the transition. METHODS: This two-wave survey recruited 1269 young adults (Mean age = 24.0 years, 70.1% males) in Hong Kong. The participants completed the Suicidal Ideation Attributes Scale, Chinese Health Questionnaire, and help-seeking behaviors in 2018 and 2019. Latent profile analysis was used to classify the participants into latent classes of suicidal ideation with substantive checking under the 3-step approach. Latent transition analysis with measurement invariance examined the transition among the latent classes from 2018 to 2019 and the associations with help-seeking behaviors and change in psychological distress. RESULTS: Three latent classes of suicidal ideation were identified and over two-thirds of the participants belonged to the Low-risk class with minimal suicidal ideation. The prevalence of the High-risk class dropped from 10.2 to 7.2%, while that of the Moderate-risk class remained stable from 2018 to 2019. Increases in psychological distress predicted higher probabilities to remain at or transit into more risky classes. Engagement in help-seeking behaviors showed differential transitions in suicidal ideation across time. CONCLUSION: The findings suggest three latent classes of suicidal ideation with distinct profiles among the young adults. Deterioration in psychological distress showed a temporal effect on worsening of suicidal ideation over a 1-year period. Future studies should elucidate the comparative effectiveness of help-seeking behaviors via online and offline channels.

Relationship between online social support and adolescents' mental health: A systematic review and meta-analysis.

INTRODUCTION: The potential benefits of supportive interactions on social networking sites on adolescents' mental health are promising; however, no systematic evaluation has been conducted on this topic. This review examined empirical research on the relationship between social support derived from social networking sites and adolescents' mental health both theoretically and empirically. METHODS: Followed PRISMA guidelines, we conducted a systematic literature search on six English and three Chinese databases in February 2020. Four thousand one hundred and seventy-seven articles were screened first by title, then abstract, and lastly, full articles. RESULTS: Fourteen studies (five English and nine Chinese) were identified, with total sample of 11,616 adolescents (age: 10-19 years; females: 42.7%-56.3%). Meta-analysis showed that the correlation of online social support with self-esteem was moderate and significant (r = .29), but with depression was small and insignificant (r = -.09). Sensitivity analysis indicated that social support from acquaintances on the internet may not be as beneficial as from real-life acquaintances. Despite that there isn't enough research on other specific mental health outcomes to run a quantitative synthesis, individual studies suggest that online social support (OSS) may be associated with increased self-identity and life satisfaction, decreased loneliness and social anxiety, it also counteracts the negative effect of stress and cyberbullying on mental health. CONCLUSIONS: OSS might be beneficial for adolescents' mental health, especially self-esteem, although the causal relationship requires longitudinal studies to confirm, and the underlying mechanisms need further investigation.

The Relationship Between Images Posted by New Mothers on WeChat Moments and Postpartum Depression: Cohort Study.

BACKGROUND: As social media posts reflect users' emotions, WeChat Moments, the most popular social media platform in China, may offer a glimpse into postpartum depression in the population. OBJECTIVE: This study aimed to investigate the features of the images that mothers posted on WeChat Moments after childbirth and to explore the correlation between these features and the mothers' risk of postpartum depression. METHODS: We collected the data of 419 mothers after delivery, including their demographics, factors associated with postpartum depression, and images posted on WeChat Moments. Postpartum depression was measured using the Edinburgh Postnatal Depression Scale. Descriptive analyses were performed to assess the following: content of the images, presence of people, the people's facial expressions, and whether or not memes were posted on WeChat Moments. Logistic regression analyses were used to identify the image features associated with postpartum depression. RESULTS: Compared with pictures of other people, we found that pictures of their children comprised the majority (3909/6887, 56.8%) of the pictures posted by the mothers on WeChat Moments. Among the posts showing facial expressions or memes, more positive than negative emotions were expressed. Women who posted selfies during the postpartum period were more likely to have postpartum depression (P=.003; odds ratio 2.27, 95% CI 1.33-3.87). CONCLUSIONS: The vast majority of mothers posted images conveying positive emotions during the postpartum period, but these images may have masked their depression. New mothers who have posted selfies may be at a higher risk of postpartum depression. TRIAL REGISTRATION: International Clinical Trials Registry Platform ChiCTR-ROC-16009255; http://www.chictr.org.cn/showproj.aspx?proj=15699.

Do Search Engine Helpline Notices Aid in Preventing Suicide? Analysis of Archival Data.

BACKGROUND: Search engines display helpline notices when people query for suicide-related information. OBJECTIVE: In this study, we aimed to examine if these notices and other information displayed in response to suicide-related queries are correlated with subsequent searches for suicide prevention rather than harmful information. METHODS: Anonymous suicide-related searches made on Bing and Google in the United States, the United Kingdom, Hong Kong, and Taiwan in a span of 10 months were extracted. Descriptive analyses and regression models were fit to the data to assess the correlation with observed behaviors. RESULTS: Display of helpline notices was not associated with an observed change in the likelihood of or future suicide searches (P=.42). No statistically significant differences were observed in the likelihood of people making future suicide queries (both generally and specific types of suicide queries) when comparing search engines in locations that display helpline notices versus ones that do not. Pages with higher rank, being neutral to suicide, and those shown among more antisuicide pages were more likely to be clicked on. Having more antisuicide Web pages displayed was the only factor associated with further searches for suicide prevention information (hazard=1.18, P=.002). CONCLUSIONS: Helpline notices are not associated with harm. If they cause positive change in search behavior, it is small. This is possibly because of the variability in intent of users seeking suicide-related information. Nonetheless, helpline notice should be displayed, but more efforts should be made to improve the visibility and ranking of suicide prevention Web pages.

Intergenerational support, satisfaction with parent-child relationship and elderly parents' life satisfaction in Hong Kong.

OBJECTIVES: This study examines in what exchange patterns that three types of intergenerational support are associated with elderly parents' life satisfaction, and whether elderly parents' evaluation on parent-child relationship plays a mediation role on those associations. METHOD: Data were drawn from Hong Kong Panel Survey for Poverty Alleviation. Respondents aged 65 and over were included ( N=504). Three types of support, namely, daily-living, financial, and emotional support were examined in four patterns-the over-benefited , under-benefited , reciprocal and no flow of exchange. A multivariable linear regression was applied to investigate the association between pattern of intergenerational exchange and life satisfaction, and mediation analysis was employed to examine the mediating role of satisfaction with parent-child relationship on their associations. RESULTS: Elderly parents were less satisfied with their lives when they had no flow of exchange in daily-living support, and more satisfied when they were under-benefited in financial support, and over-benefited or reciprocal in emotional support. Elderly parents' satisfaction with parent-child relationship mediated the association between exchange of emotional support and life satisfaction; but not the association between daily-living or financial support and life satisfaction. CONCLUSION: Different types of intergenerational support are associated with elderly parents' life satisfaction in different patterns.

Designing Microblog Direct Messages to Engage Social Media Users With Suicide Ideation: Interview and Survey Study on Weibo.

BACKGROUND: While Web-based interventions can be efficacious, engaging a target population's attention remains challenging. We argue that strategies to draw such a population's attention should be tailored to meet its needs. Increasing user engagement in online suicide intervention development requires feedback from this group to prevent people who have suicide ideation from seeking treatment. OBJECTIVE: The goal of this study was to solicit feedback on the acceptability of the content of messaging from social media users with suicide ideation. To overcome the common concern of lack of engagement in online interventions and to ensure effective learning from the message, this research employs a customized design of both content and length of the message. METHODS: In study 1, 17 participants suffering from suicide ideation were recruited. The first (n=8) group conversed with a professional suicide intervention doctor about its attitudes and suggestions for a direct message intervention. To ensure the reliability and consistency of the result, an identical interview was conducted for the second group (n=9). Based on the collected data, questionnaires about this intervention were formed. Study 2 recruited 4222 microblog users with suicide ideation via the Internet. RESULTS: The results of the group interviews in study 1 yielded little difference regarding the interview results; this difference may relate to the 2 groups' varied perceptions of direct message design. However, most participants reported that they would be most drawn to an intervention where they knew that the account was reliable. Out of 4222 microblog users, we received responses from 725 with completed questionnaires; 78.62% (570/725) participants were not opposed to online suicide intervention and they valued the link for extra suicide intervention information as long as the account appeared to be trustworthy. Their attitudes toward the intervention and the account were similar to those from study 1, and 3 important elements were found pertaining to the direct message: reliability of account name, brevity of the message, and details of the phone numbers of psychological intervention centers and psychological assessment. CONCLUSIONS: This paper proposed strategies for engaging target populations in online suicide interventions.

Assessing Suicide Risk and Emotional Distress in Chinese Social Media: A Text Mining and Machine Learning Study.

BACKGROUND: Early identification and intervention are imperative for suicide prevention. However, at-risk people often neither seek help nor take professional assessment. A tool to automatically assess their risk levels in natural settings can increase the opportunity for early intervention. OBJECTIVE: The aim of this study was to explore whether computerized language analysis methods can be utilized to assess one's suicide risk and emotional distress in Chinese social media. METHODS: A Web-based survey of Chinese social media (ie, Weibo) users was conducted to measure their suicide risk factors including suicide probability, Weibo suicide communication (WSC), depression, anxiety, and stress levels. Participants' Weibo posts published in the public domain were also downloaded with their consent. The Weibo posts were parsed and fitted into Simplified Chinese-Linguistic Inquiry and Word Count (SC-LIWC) categories. The associations between SC-LIWC features and the 5 suicide risk factors were examined by logistic regression. Furthermore, the support vector machine (SVM) model was applied based on the language features to automatically classify whether a Weibo user exhibited any of the 5 risk factors. RESULTS: A total of 974 Weibo users participated in the survey. Those with high suicide probability were marked by a higher usage of pronoun (odds ratio, OR=1.18, P=.001), prepend words (OR=1.49, P=.02), multifunction words (OR=1.12, P=.04), a lower usage of verb (OR=0.78, P<.001), and a greater total word count (OR=1.007, P=.008). Second-person plural was positively associated with severe depression (OR=8.36, P=.01) and stress (OR=11, P=.005), whereas work-related words were negatively associated with WSC (OR=0.71, P=.008), severe depression (OR=0.56, P=.005), and anxiety (OR=0.77, P=.02). Inconsistently, third-person plural was found to be negatively associated with WSC (OR=0.02, P=.047) but positively with severe stress (OR=41.3, P=.04). Achievement-related words were positively associated with depression (OR=1.68, P=.003), whereas health- (OR=2.36, P=.004) and death-related (OR=2.60, P=.01) words positively associated with stress. The machine classifiers did not achieve satisfying performance in the full sample set but could classify high suicide probability (area under the curve, AUC=0.61, P=.04) and severe anxiety (AUC=0.75, P<.001) among those who have exhibited WSC. CONCLUSIONS: SC-LIWC is useful to examine language markers of suicide risk and emotional distress in Chinese social media and can identify characteristics different from previous findings in the English literature. Some findings are leading to new hypotheses for future verification. Machine classifiers based on SC-LIWC features are promising but still require further optimization for application in real life.

The association of trends in charcoal-burning suicide with Google search and newspaper reporting in Taiwan: a time series analysis.

PURPOSE: Some East/Southeast Asian countries have experienced a rapid increase in suicide by charcoal burning over the past decade. Media reporting and Internet use were thought to contribute to the epidemic. We investigated the association between method-specific suicide incidence and both Internet search volume and newspaper reporting in Taiwan. METHOD: Weekly data for suicide, suicide-related Google search volume, and the number of articles reporting suicide in four major newspapers in Taiwan during 2008-2011 were obtained. Poisson autoregressive regression models were used to examine the associations between these variables. RESULTS: In the fully adjusted models, every 10 % increase in Google searches was associated with a 4.3 % [95 % confidence interval (CI) 1.1-7.6 %] increase in charcoal-burning suicide incidence in the same week, and a 3.8 % (95 % CI 0.4-7.2 %) increase in the following week. A one-article increase in the United Daily was associated with a 3.6 % (95 % CI 1.5-5.8 %) increase in charcoal-burning suicide in the same week. By contrast, non-charcoal-burning suicide was not associated with Google search volume, but was associated with the Apple Daily's reporting in the preceding week. CONCLUSIONS: We found that increased Internet searches for charcoal-burning suicide appeared to be associated with a subsequent increase in suicide by this method. The prevention of suicide using emerging methods may include monitoring and regulating online information that provides details of these methods as well as encouraging Internet service providers to provide help-seeking information.

A metal-semiconductor-metal detector based on ZnO nanowires grown on a graphene layer.

High quality ZnO nanowires (NWs) were grown on a graphene layer by a hydrothermal method. The ZnO NWs revealed higher uniform surface morphology and better structural properties than ZnO NWs grown on SiO2/Si substrate. A low dark current metal-semiconductor-metal photodetector based on ZnO NWs with Au Schottky contact has also been fabricated. The photodetector displays a low dark current of 1.53 nA at 1 V bias and a large UV-to-visible rejection ratio (up to four orders), which are significantly improved compared to conventional ZnO NW photodetectors. The improvement in UV detection performance is attributed to the existence of a surface plasmon at the interface of the ZnO and the graphene.

Editorial for Special Issue "Functional Graphene-Based Nanodevices".

As a typical ultra-thin two-dimensional nanomaterial, graphene has many excellent properties, including, but not limited to, mechanical, optical, thermal and electrical properties [...].

High-Performance Graphene Nanowalls/Si Self-Powered Photodetectors with HfO2 as an Interfacial Layer.

Graphene/silicon (Si) heterojunction photodetectors are widely studied in detecting of optical signals from near-infrared to visible light. However, the performance of graphene/Si photodetectors is limited by defects created in the growth process and surface recombination at the interface. Herein, a remote plasma-enhanced chemical vapor deposition is introduced to directly grow graphene nanowalls (GNWs) at a low power of 300 W, which can effectively improve the growth rate and reduce defects. Moreover, hafnium oxide (HfO2) with thicknesses ranging from 1 to 5 nm grown by atomic layer deposition has been employed as an interfacial layer for the GNWs/Si heterojunction photodetector. It is shown that the high-k dielectric layer of HfO2 acts as an electron-blocking and hole transport layer, which minimizes the recombination and reduces the dark current. At an optimized thickness of 3 nm HfO2, a low dark current of 3.85 × 10-10, with a responsivity of 0.19 AW-1, a specific detectivity of 1.38 × 1012 as well as an external quantum efficiency of 47.1% at zero bias, can be obtained for the fabricated GNWs/HfO2/Si photodetector. This work demonstrates a universal strategy to fabricate high-performance graphene/Si photodetectors.

Examination of Web-Based Single-Session Growth Mindset Interventions for Reducing Adolescent Anxiety: Study Protocol of a 3-Arm Cluster Randomized Controlled Trial.

BACKGROUND: Anxiety disorders are the most common mental disorders worldwide. In Hong Kong, 7% of adolescents are diagnosed with anxiety disorders, and 1 in every 4 secondary school students reports clinical-level anxiety symptoms. However, 65% of them do not access services. Long waitlists in public services, the high cost of private services, or the fear of being stigmatized can hinder service access. The high prevalence of anxiety and low intervention uptake indicate a pressing need to develop timely, scalable, and potent interventions suitable for adolescents. Single-session interventions (SSIs) have the potential to be scalable interventions for diagnosable or subclinical psychopathology in adolescents. Providing precise and context-adapted intervention is the key to achieving intervention efficacy. OBJECTIVE: This study aims to compare the effectiveness of three SSIs: single-session intervention of growth mindset on negative emotions (SIGMA), SSI of growth mindset of personality (SSI-GP), and active control, in reducing adolescent anxiety. METHODS: Adolescents (N=549, ages 12-16 years) from secondary schools will be randomized to 1 of 3 intervention conditions: the SIGMA, SSI-GP, or active control. The implementation of each intervention is approximately 45 minutes in length. Adolescent participants will report anxiety symptoms (primary outcome), perceived control, hopelessness, attitude toward help-seeking, and psychological well-being at preintervention, the 2-week follow-up, and the 8-week follow-up. A pilot test has confirmed the feasibility and acceptability of SIGMA among adolescents. We hypothesized that SIGMA and SSI-GP will result in a larger reduction in anxiety symptoms than the control intervention during the posttest and 8-week follow-up period. We also predict that SIGMA will have a more significant effect than SSI-GP. We will use the intention-to-treat principle and linear regression-based maximum likelihood multilevel models for data analysis. RESULTS: This study will be conducted from December 2022 to December 2023, with results expected to be available in January 2024. CONCLUSIONS: This protocol introduces the implementation content and strategies of growth mindset SSIs (consists of 2 forms: SIGMA and SSI-GP) among school students. The study will provide evidence on the efficacy of different growth mindset SSIs for adolescent anxiety. It will also establish implementation strategies for self-administrative SSIs among school students, which can serve as a pioneer implementation of a scalable and self-accessible brief intervention to improve the well-being of young people. TRIAL REGISTRATION: ClinicalTrials.gov NCT05027880; https://clinicaltrials.gov/ct2/show/NCT05027880. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/41758.

Uncovering sample heterogeneity in gaming and social withdrawal behaviors in adolescent and young adult gamers in Hong Kong.

OBJECTIVE: The current study aimed to examine the latent heterogeneity of gaming and social withdrawal behaviors in internet gamers and their associations with help-seeking behaviors. METHOD: The present study recruited 3430 young people (1874 adolescents and 1556 young adults) in Hong Kong in 2019. The participants completed the Internet Gaming Disorder (IGD) Scale, Hikikomori Questionnaire, and measures on gaming characteristics, depression, help-seeking, and suicidality. Factor mixture analysis was used to classify the participants into latent classes based on their latent factors of IGD and hikikomori in separate age groups. Latent class regressions examined the associations between help-seeking and suicidality. RESULTS: Both adolescents and young adults supported a 4-class, 2-factor model on gaming and social withdrawal behaviors. Over two-third of the sample were classified as healthy or low-risk gamers with low IGD factor means and low prevalence of hikikomori. Around one-fourth was moderate-risk gamers with elevated prevalence of hikikomori, higher IGD symptoms and psychological distress. A minority of the sample (3.8%-5.8%) belonged to high-risk gamers with the highest IGD symptoms and prevalence of hikikomori and heightened suicidal risks. Help-seeking in low-risk and moderate-risk gamers was positively associated with depressive symptoms and negatively associated with suicidal ideation. Perceived usefulness of help-seeking was significantly linked with lower likelihoods of suicidal ideation in the moderate-risk gamers and suicide attempt in the high-risk gamers. CONCLUSIONS: The present findings explicate the latent heterogeneity of gaming and social withdrawal behaviors and associated factors on help-seeking and suicidality among internet gamers in Hong Kong.

Property-performance control of multidimensional, hierarchical, single-crystalline ZnO nanoarchitectures.

Diverse morphologies of multidimensional hierarchical single-crystalline ZnO nanoarchitectures including nanoflowers, nanobelts, and nanowires are obtained by use of a simple thermal evaporation and vapour-phase transport deposition technique by placing Au-coated silicon substrates in different positions inside a furnace at process temperatures as low as 550 °C. The nucleation and growth of ZnO nanostructures are governed by the vapour-solid mechanism, as opposed to the commonly reported vapour-liquid-solid mechanism, when gold is used in the process. The morphological, structural, compositional and optical properties of the synthesized ZnO nanostructures can be effectively tailored by means of the experimental parameters, and these properties are closely related to the local growth temperature and gas-phase supersaturation at the sample position. In particular, room-temperature photoluminescence measurements reveal an intense near-band-edge ultraviolet emission at about 386 nm for nanobelts and nanoflowers, which suggests that these nanostructures are of sufficient quality for applications in, for example, optoelectronic devices.

Measuring Online Social Support: Development and Validation of a Short Form for Chinese Adolescents.

Supportive interactions on social media have great potential to benefit adolescents' development. However, there is no instrument to measure online social support (OSS) in China. The study aimed to develop and validate a Chinese short version of the Online Social Support Scale (OSSS). The original scale was translated into Chinese through multiple forward and backward translation protocols. The calibration sample (N = 262) was used to select items and test the reliability, validity, and internal structure of the short form. The cross-validation sample (N = 267) was then used to assess measurement invariance by multigroup confirmatory factor analysis and examine criterion validity based on its relationships with life satisfaction, depression, and time on social media. The 20-item Chinese short version of OSSS (OSSS-CS) includes four factors: esteem/emotional support, social companionship, informational support, and instrumental support. Our results suggest that the OSSS-CS has high internal consistency, construct validity, and criterion validity. Furthermore, evidence of partial cross-validity demonstrated invariance of the variance-covariance matrices, factor structure, factor loadings, and factor variance across independent samples. The results also revealed that the original OSSS could be replicated across cultures. Finally, the short form developed in the study can be used as a reliable and valid measure of online social support among the Chinese adolescent population.

Online Peer-Support Group's Role in Addressing Filipino Domestic Workers' Social Support Needs: Content and Social Media Metrics Analysis.

The study aimed to examine what types of social support a prominent online peer support group has provided to Filipino domestic workers (FDWs) in Hong Kong (HK), how impactful each type of support was, and to what extent the support could address group members' expressed needs. Posts published from 1 September 2021 to 31 December 2021 in one of the largest online peer-support groups for FDWs in HK and their meta-data were extracted from Facebook. Thematic content analysis was performed to extract relevant information from the posts. Descriptive statistical analysis on the social media metrics was conducted to measure post impacts. A total of 599 posts published over the study period can be categorized to provide informational (76.67%), emotional (33.56%), and instrumental support (13.52%). Posts including emotional support were often more impactful. A total of 58 posts responded to requests explicitly expressed by individual FDWs, of which 13 required external resources. The online peer-support group acts as a new channel to raise FDWs' awareness of important issues related to their well-being, to encourage and facilitate them to seek formal and informal help, and to keep them emotionally attended to. Formal support services should recognize and collaborate with them and support their long-term sustainability.

Peer Support and Mental Health of Migrant Domestic Workers: A Scoping Review.

The effectiveness of peer support in improving mental health and well-being has been well documented for vulnerable populations. However, how peer support is delivered to migrant domestic workers (MDWs) to support their mental health is still unknown. This scoping review aimed to synthesize evidence on existing peer support services for improving mental health among MDWs. We systematically searched eight electronic databases, as well as grey literature. Two reviewers independently performed title/abstract and full-text screening, and data extraction. Twelve articles were finally included. Two types of peer support were identified from the included studies, i.e., mutual aid and para-professional trained peer support. MDWs mainly seek support from peers through mutual aid for emotional comfort. The study's findings suggest that the para-professional peer support training program was highly feasible and culturally appropriate for MDWs. However, several barriers were identified to affect the successful implementation of peer support, such as concerns about emotion contagion among peers, worries about disclosure of personal information, and lack of support from health professionals. Culture-specific peer support programs should be developed in the future to overcome these barriers to promote more effective mental health practices.

The Foxconn suicides and their media prominence: is the Werther Effect applicable in China?

BACKGROUND: Media reporting of suicide and its relationship with actual suicide has rarely been investigated in Mainland China. The "Foxconn suicides" is a description referring to a string of suicides/attempts during 2010, all of which were related to a giant electrical manufacturing company, Foxconn. This study aimed to examine the clustering and copycat effects of the Foxconn suicides, and to investigate temporal patterns in how they were reported by the media in Mainland China, Hong Kong (HK), and Taiwan (TW). METHODS: Relevant articles were collected from representative newspapers published in three big cities in Mainland China (Beijing (BJ), Shenzhen (SZ), and Guangzhou (GZ)), HK, and TW, together with searching intensity data on the topic conducted using the Baidu search engine in Mainland China. The temporal clustering effects of the Foxconn suicides and their media prominence were assessed using the Kolmogorov-Smirnov test. The media reports of the Foxconn suicides' temporal patterns were explored using a nonparametric curve estimation method (that is, the local linear method). The potential mutual interactions between the Foxconn suicides and their media prominence were also examined, using logistic and Poisson regression methods. RESULTS: The results support a temporal clustering effect for the Foxconn suicides. The BJ-based newspapers' reporting and the occurrence of a Foxconn suicide/attempt are each found to be associated with an elevated chance of a further Foxconn suicide 3 days later. The occurrence of a Foxconn suicide also immediately influenced the intensity of both Baidu searching and newspaper reporting. Regional diversity in suicide reporting tempo-patterns within Mainland China, and similarities between HK and TW, are also demonstrated. CONCLUSIONS: The Foxconn suicides were temporally clustered. Their occurrences were influenced by the reporting of BJ-based newspapers, and contagion within the company itself. Further suicide research and prevention work in China should consider its special media environment.

Applying text mining methods to suicide research.

OBJECTIVE: To introduce the research methods of computerized text mining and its possible applications in suicide research and to demonstrate the procedures of applying a specific text mining area, document classification, to a suicide-related study. METHOD: A systematic search of academic papers that applied text mining methods to suicide research was conducted. Relevant papers were reviewed focusing on their research objectives and sources of data. Furthermore, a case of using natural language processing and document classification methods to analyze a large amount of suicide news was elaborated to showcase the methods. RESULTS: Eighty-six papers using text mining methods for suicide research have been published since 2001. The most common research objective (72.1%) was to classify which documents exhibit suicide risk or were written by suicidal people. The most frequently used data source was online social media posts (45.3%), followed by e-healthcare records (25.6%). For the news classification case, the top three classifiers trained for classification tasks achieved 84% or higher accuracy. CONCLUSIONS: Computerized text mining methods can help to scale up content analysis capacity and efficiency and uncover new insights and perspectives for suicide research.