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Discrete Choice Analysis of Temporal Factors on Social Network Growth

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Intelligent Information Management 2024年第1期16卷 21-34页

作者： kwok-wai cheung Yuk Tai Siu School of Communication The Hang Seng University of Hong Kong Hong Kong China

Social networks like Facebook, X (Twitter), and LinkedIn provide an interaction and communication environment for users to generate and share content, allowing for the observation of social behaviours in the digital world. These networks can be viewed as a collection of nodes and edges, where users and their interactions are represented as nodes and the connections between them as edges. Understanding the factors that contribute to the formation of these edges is important for studying network structure and processes. This knowledge can be applied to various areas such as identifying communities, recommending friends, and targeting online advertisements. Several factors, including node popularity and friends-of-friends relationships, influence edge formation and network growth. This research focuses on the temporal activity of nodes and its impact on edge formation. Specifically, the study examines how the minimum age of friends-of-friends edges and the average age of all edges connected to potential target nodes influence the formation of network edges. Discrete choice analysis is used to analyse the combined effect of these temporal factors and other well-known attributes like node degree (i.e., the number of connections a node has) and network distance between nodes. The findings reveal that temporal properties have a similar impact as network proximity in predicting the creation of links. By incorporating temporal features into the models, the accuracy of link prediction can be further improved.

关键词： Discrete Choice Models Temporal Factors Social Network Link Prediction Network Growth

Critical Reflections on the Deconvergence of Information and Communications Technology

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Intelligent Information Management 2023年第4期15卷 243-258页

作者： Zhaoxun Song Yuk Tai Siu kwok-wai cheung School of Communication The Hang Seng University of Hong Kong Hong Kong China

In recent years, information and communications technology (ICT) has gone through a process of convergence due to dynamic marketing and technological development. However, signs of deconvergence have emerged during this ongoing process of ICT convergence, which requires close attention and critical reflection by ICT practitioners and educators. This article seeks to identify and critique the seemingly paradoxical trend of market convergence/deconvergence, technological convergence/deconvergence, and audience convergence/deconvergence in ICT. To achieve this goal, a focus group discussion with eight selected participants was adopted as the research method for this study. The data were then analysed using qualitative thematic analysis. The themes revealed in the focus group discussion not only reflect the trends in ICT convergence but also, from various perspectives, highlight the increasingly obvious phenomena of deconvergence. The findings should inform industrial practitioners about the rapidly changing ICT landscape and shed light on future ICT policy and industry directions.

关键词： ICT Deconvergence Market Deconvergence Technological Deconvergence Audience Deconvergence

Application of Big Data analysis in gastrointestinal research

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World Journal of Gastroenterology 2019年第24期25卷 2990-3008页

作者： Ka-Shing cheung wai K Leung wai-Kay Seto Department of Medicine The University of Hong KongQueen Mary HospitalHong KongChina Department of Medicine The University of Hong Kong- Shenzhen HospitalShenzhen 518053Guangdong ProvinceChina

Big Data,which are characterized by certain unique traits like volume,velocity and value,have revolutionized the research of multiple fields including *** Data in health care are defined as large datasets that are collected routinely or automatically,and stored *** the rapidly expanding volume of health data collection,it is envisioned that the Big Data approach can improve not only individual health,but also the performance of health care *** application of Big Data analysis in the field of gastroenterology and hepatology research has also opened new research *** it retains most of the advantages and avoids some of the disadvantages of traditional observational studies(case-control and prospective cohort studies),it allows for phenomapping of disease heterogeneity,enhancement of drug safety,as well as development of precision medicine,prediction models and personalized *** randomized controlled trials,it reflects the real-world situation and studies patients who are often under-represented in randomized controlled ***,residual and/or unmeasured confounding remains a major concern,which requires meticulous study design and various statistical adjustment *** potential drawbacks include data validity,missing data,incomplete data capture due to the unavailability of diagnosis codes for certain clinical situations,and individual *** continuous technological advances,some of the current limitations with Big Data may be further *** review will illustrate the use of Big Data research on gastrointestinal and liver diseases using recently published examples.

关键词： Healthcare dataset Epidemiology Gastric cancer Inflammatory bowel disease Colorectal cancer Hepatocellular carcinoma Gastrointestinal bleeding

Gastrointestinal bleeding in patients on novel oral anticoagulants:Risk,prevention and management

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World Journal of Gastroenterology 2017年第11期23卷 1954-1963页

作者： Ka-Shing cheung wai K Leung Department of Medicine The University of Hong KongQueen Mary HospitalHong KongChina

Novel oral anticoagulants(NOACs), which include direct thrombin inhibitor(dabigatran) and direct factor Xa inhibitors(rivaroxaban, apixaban and edoxaban), are gaining popularity in the prevention of embolic stroke in non-valvular atrial fibrillation as well as in the prevention and treatment of venous thromboembolism. However, similar to traditional anticoagulants, NOACs have the side effects of bleeding, including gastrointestinal bleeding(GIB). Results from both randomized clinical trials and observations studies suggest that high-dose dabigatran(150 mg b.i.d), rivaroxaban and high-dose edoxaban(60 mg daily) are associated with a higher risk of GIB compared with warfarin. Other risk factors of NOAC-related GIB include concomitant use of ulcerogenic agents, older age, renal impairment, Helicobacter pylori infection and a past history of GIB. Prevention of NOAC-related GIB includes proper patient selection, using a lower dose of certain NOACs and in patients with renal impairment, correction of modifiable risk factors, and prescription of gastroprotective agents. Overt GIB can be managed by withholding NOACs followed by delayed endoscopic treatment. In severe bleeding, additional measures include administration of activated charcoal, use of specific reversal agents such as idarucizumab for dabigatran and andexanent alfa for factor Xa inhibitors, and urgent endoscopic management.

关键词： Warfarin Endoscopy Apixaban Edoxaban Gastrointestinal bleeding Dabigatran Rivaroxaban Novel anticoagulants

Model Checking for a General Linear Model with Nonignorable Missing Covariates

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Acta Mathematicae Applicatae Sinica 2012年第1期28卷 99-110页

作者： Zhi-hua SUN wai-cheung IP Heung WONG School of Mathematical sciences Graduate University of Chinese Academy of SciencesBeijing 100049China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China Department of Applied Mathematics Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

In this paper, we investigate the model checking problem for a general linear model with nonignorable missing covariates. We show that, without any parametric model assumption for the response probability, the least squares method yields consistent estimators for the linear model even if only the complete data are applied. This makes it feasible to propose two testing procedures for the corresponding model checking problem： a score type lack-of-fit test and a test based on the empirical process. The asymptotic properties of the test statistics are investigated. Both tests are shown to have asymptotic power 1 for local alternatives converging to the null at the rate n-r, 0 ≤ r 〈 1/2. Simulation results show that both tests perform satisfactorily.

关键词： general linear model model checking nonignorable missing covariates sensitivity analysis

Wavelets in probability and statistics——A review in recent advances

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Chinese Science Bulletin 2002年第9期47卷 705-716页

作者： XIE Zhongjie Heung Wong wai-cheung Ip School of Mathematical Sciences Peking UniversityBeijing 100871China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina

The main purpose of this paper is to give a review on recent advances of wavelet in probability and statistics. Many interesting new ideas, new results and new methods are introduced in this review. From many aspects of this paper, probability and statistics researchers may find many new interesting research topics for further studying on wavelets in stochastic processes. New results, such as K- sta-tionarity, wavelet representation of Karhunen processes, hidden periodicities analysis by wavelet approach, hetero-scedasticity in wavelet regression, wavelets and neural networks, etc. are introduced in this paper. Comments, discussions and plentiful references are also involved in this review.

关键词： wavelets K-stationarity time varying spectral analysis nonlinear modeling wavelet variance.

Aryl Diazonium Salt-Triggered Cyclization a nd Cycloaddition Reactions: Past, Present, and Future

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Chinese Journal of Chemistry 2020年第10期38卷 1132-1152页

作者： Fa-Guang Zhang Zhen Chen Chi wai cheung Jun-An Ma Department of Chemistry Tianjin Key Laboratory of Molecular Optoelectronic SciencesFrontiers Science Center for Synthetic Biology(Ministry of Education)and Tianjin Collaborative Innovation Center of Chemical Science&EngineeringTinjin UniversityTianjin 300072China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207FujianChina

Aryl diazonium salts occupy a privileged role in synthetic chemistry owing to their ready availability and versatile *** their applications in accessing diversely functionalized arene derivatives via denitrogenation-coupling and reduction/addition reactions have been well recognized by practitioners in both academia and industry,recent renaissance in chemical transformations of retaining the key N2-unit has emerged as a powerful technique to construct various A/-*** review covers the history and latest advances in cyclization and cycloaddition reactions using aryl diazonium salts as N2-annulation *** scope,applications,and opportunities in exploring new chemical space by this sustainable strategy are summarized and discussed.

关键词： salts summarized retaining

Cancer stem-like cells in Epstein-Barr virus-associated nasopharyngeal carcinoma

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Chinese Journal of Cancer 2014年第11期33卷 529-538页

作者： Samantha Wei-Man Lun Siu-Tim cheung kwok-wai Lo Department of Anatomical and Cellular Pathology State Key Laboratory in Oncology in South ChinaPrince of Wales Hospital Department of Surgery The University of Hong Kong Li Ka Shing Institute of Health Science The Chinese University of Hong Kong

Although the Epstein-Barr virus(EBV) has spread to all populations in the world, EBV-associated nasopharyngeal carcinoma(NPC) is prevalent only in South China and Southeast Asia. The role of EBV in the malignant transformation of nasopharyngeal epithelium is the main focus of current researches. Radiotherapy and chemoradiotherapy have been successful in treating early stage NPC, but the recurrence rates remain high. Unfortunately, local relapse and metastasis are commonly unresponsive to conventional treatments. These recurrent and metastatic lesions are believed to arise from residual or surviving cells that have the properties of cancer stem cells. These cancer stem-like cells(CSCs) have the ability to selfrenew, differentiate, and sustain propagation. They are also chemo-resistant and can form spheres in anchorage-independent environments. This review summarizes recent researches on the CSCs in EBVassociated NPC, including the findings regarding cell surface markers, stem cell-related transcription factors, and various signaling pathways. In particular, the review focuses on the roles of EBV latent genes [latent membrane protein 1(LMP1) and latent membrane protein 2A(LMP2A)], cellular microRNAs, and adenosine triphosphate(ATP)-binding cassette chemodrug transporters in contributing to the properties of CSCs, including the epithelial-mesenchymal transition, stem-like transition, and chemo-resistance. Novel therapeutics that enhance the efficacy of radiotherapy and chemoradiotherapy and inhibitors that suppress the properties of CSCs are also discussed.

关键词：肿瘤干细胞 EB病毒鼻咽癌潜伏膜蛋白1 上皮细胞东南亚地区三磷酸腺苷 EBV

Risk of gastric cancer development after eradication of Helicobacter pylori

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World Journal of Gastrointestinal Oncology 2018年第5期10卷 115-123页

作者： Ka-Shing cheung wai K Leung Department of Medicine The University of Hong Kong Queen Mary Hospital

Helicobacter pylori(H. pylori) infection is the most important risk factor for gastric cancer(gc) development through the correa's gastric carcinogenesis cascade. However, H. pylori eradication alone does not eliminate gc, as pre-neoplastic lesions(atrophic gastritis, intestinal metaplasia and dysplasia) may have already developed in some patients. It is therefore necessary to identify patients at high-risk for gastric cancer after H. pylori eradication to streamline the management plan. If the patients have not undergone endoscopy with histologic assessment, the identification of certain clinical risk factors and non-invasive testing(serum pepsinogen) can predict the risk of atrophic gastritis. For those with suspected atrophic gastritis, further risk stratification by endoscopy with histologic assessment according to validated histologic staging systems would be advisable. Patients with higher stages may require long-term endoscopic surveillance. Apart from secondary prevention to reduce deaths by diagnosing gc at an early stage, identifying medications that could potentially modify the gc risk would be desirable. The potential roles of a number of medications have been suggested by various studies, including proton pump inhibitors(PPIs), aspirin, statins and metformin. However, there are currently no randomized clinical trials to address the impact of these medications on gc risk after H. pylori eradication. In addition, most of these studies failed to adjust for the effect of concurrent medications on gc risk. Recently, large population-based retrospective cohort studies have shown that PPIs were associated with an increased gc risk after H. pylori eradication, while aspirin was associated with a lower risk. The roles of other agents in reducing gc risk after H. pylori eradication remain to be determined.

关键词： Gastric adenocarcinoma Stomach cancer Helicobacter pylori Chemoprevention Intestinal metaplasia