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1.
J Neurosci Methods ; 403: 110049, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38151187

RESUMO

BACKGROUND: Dynamic spatial functional network connectivity (dsFNC) has shown advantages in detecting functional alterations impacted by mental disorders using magnitude-only fMRI data. However, complete fMRI data are complex-valued with unique and useful phase information. METHODS: We propose dsFNC of spatial source phase (SSP) maps, derived from complex-valued fMRI data (named SSP-dsFNC), to capture the dynamics elicited by the phase. We compute mutual information for connectivity quantification, employ statistical analysis and Markov chains to assess dynamics, ultimately classifying schizophrenia patients (SZs) and healthy controls (HCs) based on connectivity variance and Markov chain state transitions across windows. RESULTS: SSP-dsFNC yielded greater dynamics and more significant HC-SZ differences, due to the use of complete brain information from complex-valued fMRI data. COMPARISON WITH EXISTING METHODS: Compared with magnitude-dsFNC, SSP-dsFNC detected additional and meaningful connections across windows (e.g., for right frontal parietal) and achieved 14.6% higher accuracy for classifying HCs and SZs. CONCLUSIONS: This work provides new evidence about how SSP-dsFNC could be impacted by schizophrenia, and this information could be used to identify potential imaging biomarkers for psychotic diagnosis.


Assuntos
Esquizofrenia , Humanos , Esquizofrenia/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Mapeamento Encefálico/métodos , Encéfalo/diagnóstico por imagem , Cadeias de Markov
2.
Water Res ; 246: 120686, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37812979

RESUMO

Effective and standardized monitoring methodologies are vital for successful reservoir restoration and management. Environmental DNA (eDNA) metabarcoding sequencing offers a promising alternative for biomonitoring and can overcome many limitations of traditional morphological bioassessment. Recent attempts have even shown that supervised machine learning (SML) can directly infer biotic indices (BI) from eDNA metabarcoding data, bypassing the cumbersome calculation process of BI regardless of the taxonomic assignment of eDNA sequences. However, questions surrounding the general applicability of this taxonomy-free approach to monitoring reservoir health remain unclear, including model stability, feature selection, algorithm choice, and multi-season biomonitoring. Here, we firstly developed a novel biological integrity index (Me-IBI) that integrates multitrophic interactions and environmental information, based on taxonomy-assigned eDNA metabarcoding data. The Me-IBI can better distinguish the actual health status of the Three Gorges Reservoir (TGR) than physicochemical assessments and have a clear response to human activity. Then, taking this reliable Me-IBI as a supervised label, we compared the impact of selecting different numbers of features and SML algorithms on the stability and predictive performance of the model for predicting ecological conditions in multiple seasons using taxonomy-free eDNA metabarcoding data. We discovered that even with a small number of features, different SML algorithms can establish a stable model and obtain excellent predictive performance. Finally, we proposed a four-step strategy for standardized routine biomonitoring using SML tools. Our study firstly explores the general applicability problem of the taxonomy-free eDNA-SML approach and establishes a solid foundation for the large-scale and standardized biomonitoring application.


Assuntos
DNA Ambiental , Humanos , Biodiversidade , Monitoramento Ambiental/métodos , Código de Barras de DNA Taxonômico/métodos , Aprendizado de Máquina Supervisionado , Ecossistema
3.
Empir Econ ; : 1-18, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36532712

RESUMO

Financial risk is spread and amplified through the interconnectedness among financial institutions. We apply a time-varying parameter vector autoregression model to analyze the dynamic spillover effects in the Chinese financial system. We find that the 2017 house price control policies have significantly increased the risk of China's financial system. Before 2017, with the prosperity of the real estate market, the interconnectedness of the Chinese financial system continued to decline, while after 2017, with the slowdown of house price growth and the downturn of the real estate market, the interconnectedness turned to increase. For different sectors, the trends and the magnitudes of the spillover effects are diverse, and any sector can contribute to systemic risk in a dynamic way. Finally, we rank 20 systemically important financial institutions according to two centrality measures. The stable institution ranking provides less noisy information for regulators to formulate a policy and intervene in the market effectively.

4.
Emerg Med Int ; 2022: 2901189, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36017306

RESUMO

Objective: To investigate the predictive value of preoperative nutritional risk assessment on the occurrence of complications after radical cystectomy plus urinary diversion for bladder cancer. Methods: Retrospective analysis of 178 patients with bladder cancer between July 2010 and March 2022 who underwent elective radical cystectomy plus urinary diversion was conducted. The occurrence of complications within 90 days after surgery was counted for all patients, and the postoperative complication rates of patients with and without nutritional risk were compared and analyzed. Also, logistic regression analysis was used to assess the relative risk coefficients of NRS-2002 and the occurrence of postoperative complications. Results: Comparison of clinicopathological characteristics and surgical conditions between the two groups showed that the proportion of combined diabetes mellitus, operative time, and postoperative hospital stay were higher in the nutritional risk group (NRS ≥3 score) than in the no nutritional risk group (NRS <3 score), while the preoperative blood albumin (ALB) level was lower than that in the no nutritional risk group (NRS <3 score). The results of multifactorial risk regression analysis showed that low preoperative ALB level and high NRS score were independent risk factors for postoperative complications in bladder cancer (P < 0.05). Conclusion: The NRS-2002 nutritional risk score has good predictive value for the incidence of postoperative complications in patients with bladder cancer and provides a scientific basis for perioperative nutritional support.

5.
Environ Res ; 212(Pt C): 113398, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35569539

RESUMO

To meet the increasingly stringent discharge standards of wastewater treatment plants (WWTPs) in the Taihu Lake Basin, the Chinese government successively established the National Special Water Project Program to develop new technologies to retrofit and upgrade existing wastewater treatment processes during the 11th, 12th, and 13th Five-Year Plans. However, there is a lack of systematic sorting of the existing research outcomes, and thus hinders the application and promotion of the upgrade technologies. Based on the outcomes of the National Special Water Project and a field survey, this research analyzed the current status of wastewater treatment in the Taihu Lake Basin and systematically integrated the retrofitting measures of WWTPs in terms of achieving the Grade IA of the national standard and local stricter discharge standards (DB 32/1072-2018 and DB 33/2169-2018). In particular, the boundary conditions, design parameters, specific recommendations of the technologies, and some typical engineering cases were provided accordingly. Finally, this study discussed the future development directions of WWTPs during the upgrade process from the perspective of carbon neutrality and digitalization. The present work will hopefully assist in retrofitting and constructing WWTPs to achieve the stricter effluent discharge criteria and help optimize the design and construction of WWTPs in the best way.


Assuntos
Lagos , Purificação da Água , Eliminação de Resíduos Líquidos , Águas Residuárias , Água
6.
IEEE Trans Cybern ; 52(9): 8741-8752, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33566782

RESUMO

In this article, the hidden Markov model (HMM)-based fuzzy control problem is addressed for slow sampling model nonlinear Markov jump singularly perturbed systems (SPSs), in which the general transition and mode detection information issue is considered. The general information issue is formulated as the one with not only the transition probabilities (TPs) and the mode detection probabilities (MDPs) being partly known but also with the certain estimation errors existing in the known elements of them. This formulation covers the cases with both the TPs and the MDPs being fully known, or one of them being fully known but another being partly known, or both them being partly known but without the certain estimation errors, which were considered in some previous literature. By utilizing the HMM with general information, some strictly stochastic dissipativity analysis criteria are derived for the slow sampling model nonlinear Markov jump SPSs. In addition, a unified HMM-based fuzzy controller design methodology is established for slow sampling model nonlinear Markov jump SPSs such that a fuzzy controller can be designed depending on whether the fast dynamics of the systems are available or not. A numerical example and a tunnel diode circuit are finally used to illustrate the validity of the obtained results.

8.
Front Psychol ; 12: 676063, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34335389

RESUMO

This study applied self-determination theory (SDT) to investigate the relationships between work motivation and work behaviour of Chinese employees and the moderating role of financial stress. Data were obtained from 245 employees of five organisations in China using a convenience sampling technique. The results indicated that autonomous motivation positively predicted work performance and innovative work behaviour, while controlled motivation had a positive effect only on work performance of employees. In addition, financial stress moderated the relationships between autonomous motivation and work performance and innovative work behaviour of employees. Specifically, the beneficial effect of autonomous motivation on work performance and innovative work behaviour disappeared when financial stress was high. The findings of the present study supported cultural similarities in the positive role of autonomous motivation and showed cultural differences in the role of controlled motivation. The implications of this study are also discussed.

9.
Entropy (Basel) ; 23(5)2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34065367

RESUMO

Using a unique data set containing about 15.06 million truck transportation records in five months, we investigate the highway freight transportation diversity of 338 Chinese cities based on the truck transportation probability pij from one city to another. The transportation probabilities are calculated from the radiation model based on the geographic distance and its cost-based version based on the driving distance as the proxy of cost. For each model, we consider both the population and the gross domestic product (GDP), and find quantitatively very similar results. We find that the transportation probabilities have nice power-law tails with the tail exponents close to 0.5 for all the models. The two transportation probabilities in each model fall around the diagonal pij=pji but are often not the same. In addition, the corresponding transportation probabilities calculated from the raw radiation model and the cost-based radiation model also fluctuate around the diagonal pijgeo=pijcost. We calculate four sets of highway truck transportation diversity according to the four sets of transportation probabilities that are found to be close to each other for each city pair. It is found that the population, the gross domestic product, the in-flux, and the out-flux scale as power laws with respect to the transportation diversity in the raw and cost-based radiation models. It implies that a more developed city usually has higher diversity in highway truck transportation, which reflects the fact that a more developed city usually has a more diverse economic structure.

10.
Int J Environ Health Res ; 31(7): 835-847, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31736355

RESUMO

The study aimed to analyze the level of heavy metal pollution in the agricultural lands in the southern margin of Tarim Basin, Xinjiang, and its risks to human health. A total of 1765 soil samples were collected from the Cele-Ruoqiang area. The contents of soil As, Cd, Cr, Cu, Hg, Ni, Pb and Zn were analyzed using the pollution load index method. The results showed that soil was slightly contaminated with Hg and Cd; the multivariate statistical analysis indicated that Cr, Ni, As, Cu, Zn, and Cd were formed mostly by geochemical genesis, whereas Hg and Pb contents by the geological origin and human activities. The health risk assessment showed that there is no unacceptable non-carcinogenic health risk. As levels posed carcinogenic risk, however, they were within human tolerance. Thus, this study provides a scientific basis for local agricultural production safety and prevention and control of soil heavy metal pollution.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Adulto , Agricultura , Criança , China , Monitoramento Ambiental , Poluição Ambiental/análise , Humanos , Medição de Risco
11.
Ann Emerg Med ; 76(6): 717-727, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32747080

RESUMO

STUDY OBJECTIVE: Postoverdose interventions that deploy peer recovery support specialists to emergency departments (EDs) are a promising response to opioid overdoses among patients presenting in EDs. The objective of this study was to elicit patients' perspectives regarding the feasibility and acceptability of such an intervention and to ensure that their perspectives are represented in intervention design, implementation, and evaluation. METHOD: In 2019 the study investigators conducted focus groups with people who use opioids to elicit perspectives about a postoverdose intervention delivered in the ED by using a semistructured interview guide that asked about feasibility, acceptability, perceived benefits, and concerns. Focus groups were digitally recorded, transcribed, and analyzed for emerging themes. RESULTS: Nine focus groups with 30 people who use opioids were conducted. Key findings that could improve feasibility and acceptability of the intervention include the following: the importance of balancing the urgency of seeing patients quickly with a need to accommodate the experience of precipitated withdrawal symptoms; the need to address privacy concerns; and the need to address concerns related to cost, insurance coverage, and sustainability. Perceived benefits of the intervention included the ability of the peer recovery support specialist to provide advocacy and support, serve as a model of hope and encouragement for behavior change, and fill key service gaps. CONCLUSION: Postoverdose interventions in the ED provide the opportunity to integrate harm reduction-based interventions into traditional biomedical care facilities. These interventions can fill gaps in services and provide additional care and comfort for people who use opioids, but design, implementation, and evaluation should be informed by a patient-centered care perspective.


Assuntos
Analgésicos Opioides/efeitos adversos , Aconselhamento/métodos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Grupos Focais/métodos , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Cobertura do Seguro/normas , Masculino , Pessoa de Meia-Idade , Nevada/epidemiologia , Overdose de Opiáceos/epidemiologia , Overdose de Opiáceos/mortalidade , Overdose de Opiáceos/terapia , Assistência Centrada no Paciente , Avaliação de Programas e Projetos de Saúde , Intervenção Psicossocial/métodos , Pesquisa Qualitativa , Síndrome de Abstinência a Substâncias/epidemiologia
12.
PLoS One ; 15(1): e0226667, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923180

RESUMO

Price changes are induced by aggressive market orders in stock market. We introduce a bivariate marked Hawkes process to model aggressive market order arrivals at the microstructural level. The order arrival intensity is marked by an exogenous part and two endogenous processes reflecting the self-excitation and cross-excitation respectively. We calibrate the model for a Shenzhen Stock Exchange stock. We find that the exponential kernel with a smooth cut-off (i.e. the subtraction of two exponentials) produces much better calibration than the monotonous exponential kernel (i.e. the sum of two exponentials). The exogenous baseline intensity explains the U-shaped intraday pattern. Our empirical results show that the endogenous submission clustering is mainly caused by self-excitation rather than cross-excitation.


Assuntos
Investimentos em Saúde/economia , Modelos Econômicos , Comércio/economia
13.
Artif Organs ; 44(4): 428-434, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31660615

RESUMO

This study aims to investigate the vestibular function status of cochlear implant patients using cervical vestibular evoked myogenic potential (cVEMP) testing and estimate the effects of cochlear implants on vestibular function. The cVEMPs of 50 cochlear implant patients were measured preoperatively, and at one and six months postoperatively. Then, implanted ears and non-implanted ears were compared in terms of p13/n23 wave response rates, latency, amplitude and threshold. Preoperatively, the binaural cVEMP response rate was 92%, while the cVEMP response rates of implanted ears vs. non-implanted ears at postoperative one and six months were 24% vs. 80% and 52% vs. 82%, respectively. No significant difference between implanted and non-implanted ears was found preoperatively, in terms of latent period, amplitude, or threshold. However, significant changes were found in amplitude and threshold for implanted ears after the operation, but not in latency. No significant postoperative change was found in amplitude, latent period, or threshold for non-implanted ears. Significant differences between implanted and non-implanted ears were found in both amplitude and threshold. Cochlear implants affect vestibular function, especially saccular function, and reduce the cVEMP amplitude and threshold of implanted ears.


Assuntos
Implantes Cocleares , Potenciais Evocados Miogênicos Vestibulares , Testes de Impedância Acústica , Adolescente , Adulto , Criança , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Sáculo e Utrículo/fisiologia , Adulto Jovem
14.
Huan Jing Ke Xue ; 40(9): 4042-4051, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854867

RESUMO

Pollution-induced water shortage problems have severely hindered the economic development of Kashi Prefecture in Xinjiang. In order to study the chemical characteristics and main ion sources of groundwater in the Kashgar River Delta of Western Kashi Prefecture, 402 groundwater samples and 114 groundwater hydrogen and oxygen isotope samples were collected and tested in June to October 2016. Based on the methods of mathematical statistics, Gibbs diagram, ion ratio, Schoeller diagram, and hydrogeochemical simulation, the hydrogeochemical characteristics of the groundwater were analyzed, and the hydrochemical evolution law and the main ion sources were discussed. The following results were noted. ①SO42- was the main anion in the groundwater, followed by Cl-. Na+ was the main cation, and the groundwater was mainly SO4·Cl-Na type. ②The groundwater ion components were controlled by dissolution of rocks and evaporation. The groundwater ions were mainly derived from the dissolution of evaporites, followed by the dissolution of carbonates. Unconfined groundwater in the river alluvium plain was affected by evaporation, and the confined groundwater was affected by reverse cation exchange and mixing. ③Along the groundwater flow direction, the concentration of ion components in the groundwater increased. Halite, dolomite, and gypsum were dissolved, and calcite was precipitated.

15.
Rep Prog Phys ; 82(12): 125901, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31505468

RESUMO

Multifractality is ubiquitously observed in complex natural and socioeconomic systems. Multifractal analysis provides powerful tools to understand the complex nonlinear nature of time series in diverse fields. Inspired by its striking analogy with hydrodynamic turbulence, from which the idea of multifractality originated, multifractal analysis of financial markets has bloomed, forming one of the main directions of econophysics. We review the multifractal analysis methods and multifractal models adopted in or invented for financial time series and their subtle properties, which are applicable to time series in other disciplines. We survey the cumulating evidence for the presence of multifractality in financial time series in different markets and at different time periods and discuss the sources of multifractality. The usefulness of multifractal analysis in quantifying market inefficiency, in supporting risk management and in developing other applications is presented. We finally discuss open problems and further directions of multifractal analysis.

17.
J Med Virol ; 90(1): 165-171, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28710863

RESUMO

To evaluate the effectiveness of Human papillomavirus16/18 infection referral to colposcopy in cervical cancer screening for women aged 25 years and older in Chinese northwest region Shaan'xi province. A total of 2224 women were diagnosed with primary high-risk HPV infection by HPV-DNA genotyping technology during August 2014 to August 2015. A total of 1916 cases referred for colposcopy with histological evidence were enrolled, including 1124 women with HPV16/18 genotype and 792 with other High-risk human papillomavirus genotypes. A total of 1916 women aged 25 years and older with HR-HPV positive were referred to colposcopy. The distribution of HPV16, HPV18, and other HR-HPVs infection were 49.22%, 9.45%, and 41.33%, respectively. 71.56% had normal cervical histology, 7.05% had Cervical Intraepithelial Neoplasia1, 8.82% had CIN2, 7.25% had CIN3, and 5.32% had cervical cancer. The percentage of positivity of HPV16 and HPV18 was highly associated with the relative risk of cervical lesion. The sensitivity and specificity of HPV16/18 for detection of CIN2+ (CIN3+) was 82.68% (92.12%) and 47.87% (46.15%), respectively. The positive predictive value and negative predictive value of HPV16/18 for detection of CIN2+ (CIN3+) was 30.16% (19.75%) and 91.03% (97.60%), respectively. HPV16 and HVP18 are the most common genotypes in high grade cervical lesions in Shaan'xi province. Meanwhile, these two types play predominant roles in the progression of high grade cervical lesion. Primary HPV16/18 detection has high sensitivity and negative predictive value in cervical cancer screening and the strategy for women with HPV16 and HPV18 infection referral to colposcopy is efficient and feasible in northwestern region of China.


Assuntos
Detecção Precoce de Câncer , Papillomavirus Humano 16/isolamento & purificação , Papillomavirus Humano 18/isolamento & purificação , Infecções por Papillomavirus/complicações , Infecções por Papillomavirus/diagnóstico , Displasia do Colo do Útero/diagnóstico , Neoplasias do Colo do Útero/diagnóstico , Adulto , Idoso , Colo do Útero/patologia , Colo do Útero/virologia , China/epidemiologia , Colposcopia , Feminino , Genótipo , Papillomavirus Humano 16/genética , Papillomavirus Humano 16/patogenicidade , Papillomavirus Humano 18/genética , Papillomavirus Humano 18/patogenicidade , Humanos , Pessoa de Meia-Idade , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/virologia , Valor Preditivo dos Testes , Gravidez , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/prevenção & controle , Neoplasias do Colo do Útero/virologia , Esfregaço Vaginal , Displasia do Colo do Útero/epidemiologia , Displasia do Colo do Útero/prevenção & controle , Displasia do Colo do Útero/virologia
18.
Sci Rep ; 6: 18727, 2016 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-26743687

RESUMO

Much empirical evidence shows that individuals usually exhibit significant homophily in social networks. We demonstrate, however, skill complementarity enhances heterophily in the formation of collaboration networks, where people prefer to forge social ties with people who have professions different from their own. We construct a model to quantify the heterophily by assuming that individuals choose collaborators to maximize utility. Using a huge database of online societies, we find evidence of heterophily in collaboration networks. The results of model calibration confirm the presence of heterophily. Both empirical analysis and model calibration show that the heterophilous feature is persistent along the evolution of online societies. Furthermore, the degree of skill complementarity is positively correlated with their production output. Our work sheds new light on the scientific research utility of virtual worlds for studying human behaviors in complex socioeconomic systems.


Assuntos
Redes Comunitárias/estatística & dados numéricos , Comportamento Cooperativo , Modelos Estatísticos , Rede Social , Redes Comunitárias/economia , Bases de Dados Factuais , Humanos , Ocupações , Habilidades Sociais
19.
Zhonghua Nan Ke Xue ; 22(4): 335-8, 2016 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30088705

RESUMO

Objective: To explore the treatment of vesiculitis with hemospermia by transurethral seminal vesiculoscopy. Methods: We treated 64 cases of vesiculitis with hemospermia by transurethral seminal vesiculoscopy. During the operation,we removed the stones and inflammatory substances and collected seminal vesicle fluid to be cultured for bacteria,ureaplasma urealyticum(UU),chlamydia trachomatis(CT),and mycoplasma hominis(MH),followed by infusion of levofloxacin at 0. 3 g/100 ml into the seminal vesicle. Regular follow-up was conducted post-operatively. Results: All the operations were successfully accomplished, the operation time averaging(40 ± 15) min(25- 50 min). The ejaculatory duct opening was observed on the verumontanum surface in the posterior urethra in 2 cases, abnormal passages found in the prostatic utricle in 8 cases, and seminal vesicle fenestration from the prostatic utricle conducted in the other 54 cases(32 by seminal vesiculoscopy and 22 with holmium laser). Stones were seen in the prostatic utricle in 5 cases, in the seminal vesicle in 6 cases, and in both the prostatic utricle and seminal vesicle in 2 cases. Culture of the seminal vesicle fluid showed the acinetobacter to be positive in 1 case and UU, CT, and MH to be negative. At 3 months after surgery, hemospermia was cured in 52 cases, relieved in 8,and unimproved in 4. Conclusion: Seminal vesicle fenestration drainage by transurethral seminal vesiculoscopy for the treatment of vesiculitis with hemospermia has the advantages of short operation time, high effectiveness and no obvious complications and can also be employed for the examination of the seminal vesicle as well as removal of stones and inflammatory substances.


Assuntos
Doenças dos Genitais Masculinos/cirurgia , Hemospermia/cirurgia , Inflamação/cirurgia , Glândulas Seminais/cirurgia , Líquidos Corporais , Cálculos , Chlamydia trachomatis , Drenagem , Ductos Ejaculatórios , Humanos , Lasers de Estado Sólido , Levofloxacino , Masculino , Duração da Cirurgia , Período Pós-Operatório , Próstata , Uretra
20.
PLoS One ; 10(9): e0137892, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26368537

RESUMO

This paper reexamines the profitability of loser, winner and contrarian portfolios in the Chinese stock market using monthly data of all stocks traded on the Shanghai Stock Exchange and Shenzhen Stock Exchange covering the period from January 1997 to December 2012. We find evidence of short-term and long-term contrarian profitability in the whole sample period when the estimation and holding horizons are 1 month or longer than 12 months and the annualized return of contrarian portfolios increases with the estimation and holding horizons. We perform subperiod analysis and find that the long-term contrarian effect is significant in both bullish and bearish states, while the short-term contrarian effect disappears in bullish states. We compare the performance of contrarian portfolios based on different grouping manners in the estimation period and unveil that decile grouping outperforms quintile grouping and tertile grouping, which is more evident and robust in the long run. Generally, loser portfolios and winner portfolios have positive returns and loser portfolios perform much better than winner portfolios. Both loser and winner portfolios in bullish states perform better than those in the whole sample period. In contrast, loser and winner portfolios have smaller returns in bearish states, in which loser portfolio returns are significant only in the long term and winner portfolio returns become insignificant. These results are robust to the one-month skipping between the estimation and holding periods and for the two stock exchanges. Our findings show that the Chinese stock market is not efficient in the weak form. These findings also have obvious practical implications for financial practitioners.


Assuntos
Marketing , Modelos Econômicos , China , Humanos
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