32 results on '"Stella Yiyan Li"'
Search Results
2. The social and economic outputs of SME-GSI research collaboration in an emerging economy: An ecosystem perspective
- Author
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Mariana Giovanna Andrade-Rojas, Stella Yiyan Li, and John JianJun Zhu
- Subjects
Management of Technology and Innovation ,Strategy and Management ,General Business, Management and Accounting - Published
- 2022
3. Investigating the disruptiveness of the sharing economy at the individual consumer level: How consumer reflexivity drives re-engagement in sharing
- Author
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Stella Yiyan Li, Antje R. H. Graul, and John Jianjun Zhu
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Marketing ,Economics and Econometrics ,Business and International Management - Published
- 2023
4. Online critical review classification in response strategy and service provider rating: Algorithms from heuristic processing, sentiment analysis to deep learning
- Author
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Stella Yiyan Li, Chi-Jen Chen, Yung-Chun Chang, Chih Hao Ku, and John Jianjun Zhu
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Marketing ,business.industry ,Computer science ,Deep learning ,05 social sciences ,Sentiment analysis ,Enterprise value ,Econometric analysis ,Service provider ,Hospitality industry ,Response strategy ,0502 economics and business ,050211 marketing ,Artificial intelligence ,Valence (psychology) ,business ,Algorithm ,050203 business & management - Abstract
This research proposes and tests mechanisms for defining and identifying the critical online consumer reviews that firms could prioritize to optimize their online response strategies, while incorporating the latest artificial intelligence (AI) technology to deal with the overwhelming volume of information. Three sets of analytical tools are introduced: Heuristic Processing, Linguistic Feature Analysis, and Deep Learning-based Natural Language Processing (NLP), to extract review information. Twelve algorithms to classify critical reviews were developed accordingly and empirically tested for their effectiveness. Our econometric analysis of 110,146 online reviews from a chain operation in hospitality industry over seven years identifies six outstanding algorithms. Firm value rating, comment length, valence, and certain consumer emotions, in addition to past comment-response behavior, are found to be superior in predicting incoming review criticality. However, the service attributes such as urgency to reply and the feasibility of actions to take are not as informative.
- Published
- 2021
5. What Feedback Matters? The Role of Experience in Motivating Crowdsourcing Innovation
- Author
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John Jianjun Zhu, Kimmy Wa Chan, Jian Ni, and Stella Yiyan Li
- Subjects
Social psychology (sociology) ,Peer feedback ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) ,business.industry ,media_common.quotation_subject ,Management Science and Operations Research ,Crowdsourcing ,Creativity ,Industrial and Manufacturing Engineering ,Management of Technology and Innovation ,Personnel economics ,Quality (business) ,Valence (psychology) ,business ,Psychology ,Social psychology ,media_common ,Open innovation - Abstract
Recent open innovation literature indicates increasing concern about the quality of crowdsourced ideas. Building on a framework of creativity capability, rooted in behavioral literature, and intrinsic (vs. extrinsic) motivation, derived from personnel economics and social psychology literature, this study predicts the influence of feedback on ideation performance. Specifically, the effectiveness of feedback on ideation performance in firm‐sponsored, non–financially incentivized, idea‐crowdsourcing communities may depend on its valence (positive vs. negative), source (peers vs. firm), and ideators’ ideation experience. Field data, obtained using text‐mining techniques from an idea‐crowdsourcing community, reveal that the effects of positive (negative) peer feedback for increasing (decreasing) subsequent idea quality strengthen (weaken) as ideators gain experience. However, the effects of positive (negative) firm feedback for increasing (decreasing) subsequent idea quality weaken with ideation experience. Experienced ideators are more motivated (less demotivated) to improve subsequent ideation performance when they receive positive peer (negative firm) feedback; inexperienced ideators are less motivated by negative peer feedback but more motivated by positive firm feedback. The results are robust to tests with alternative field data and model specifications, as validated by a controlled laboratory experiment. They also suggest feedback strategies that managers can use to boost customer ideation performance in crowdsourcing contexts.
- Published
- 2020
6. Passion transfer across national borders
- Author
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Megan Yuan Li, Caleb H. Tse, Shige Makino, Stella Yiyan Li, and Nanyang Business School
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Marketing ,Empirical data ,Organizational identity ,media_common.quotation_subject ,Business administration ,05 social sciences ,Subsidiary ,Passion ,Context (language use) ,General [Business] ,Incentive ,Multinational corporation ,0502 economics and business ,Multinational Corporations ,050211 marketing ,Business ,050203 business & management ,Passion Transfer ,media_common - Abstract
The transfer of a leader's passion to employees is crucial to successful innovation, but it becomes especially challenging when the organization becomes large and complex. This study examines both the antecedents and consequences of corporate leaders’ passion transfer in the context of multinational corporations (MNCs). We consider two types of passion among leaders: “self-enhancing” passion, which enhances a leader's own self-identity, and “self-transcending” passion, which helps members share an organizational identity. Our empirical data, collected at the level of the parent firm and subsidiaries, show that the successful transfer of a leader's passion from headquarters to local staff is significantly and positively associated with innovation. Passion transfer is positively affected by both types of leaders’ passion and mutual communication, and negatively affected by incentive-based organizational barriers. We also find that self-enhancing passion affects innovation both directly and indirectly through passion transfer, whereas self-transcending passion affects innovation only through passion transfer. This study was supported by the Fundamental Research Funds for the Central Universities, China (Grant Numbers: NJ2019026; NS2018050); and the Human Resource Development Research Base of Jiangsu Province, China (grant number: 2017ZSJD002).
- Published
- 2020
7. Social Media Advertising through Private Messages and Public Feeds: A Congruency Effect between Communication Channels and Advertising Appeals
- Author
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Professor Fue Zeng, Ruijuan Wang, Assistant Professor Stella Yiyan Li, and Associate Professor Zhe Qu
- Subjects
Information Systems and Management ,Information Systems ,Management Information Systems - Published
- 2022
8. Good to Be Novel? Understanding How Idea Feasibility Affects Idea Adoption Decision Making in Crowdsourcing
- Author
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Kimmy Wa Chan, John Jianjun Zhu, and Stella Yiyan Li
- Subjects
Marketing ,Knowledge management ,business.industry ,Computer science ,Heuristic ,05 social sciences ,Novelty ,Crowdsourcing ,Path of least resistance ,Paradigm shift ,0502 economics and business ,New product development ,Mediation ,Key (cryptography) ,050211 marketing ,Business and International Management ,business ,050203 business & management - Abstract
Soliciting novel ideas from the crowd is a paradigm shift for innovation that gains increasing attention from researchers and practitioners. However, studies examining the relationship between the novelty of crowdsourced ideas and firms' idea adoption decisions are surprisingly rare. This research adopts the path-of-least-resistance (POLR) theory as a new theoretical angle to examine the role of idea feasibility as a key heuristic cue mediating the effect of idea novelty on adoption decisions. We further explore factors that may amplify or mitigate this mediation. Using data collected from a laboratory experiment and a firm-sponsored crowdsourcing community, we reveal that firms tend to follow the POLR by using idea feasibility as meta-information to evaluate novel ideas in their idea adoption decisions. However, this tendency depends on external stimuli and constraints, such that the mediation of idea feasibility exists only when idea favorability from the crowd is low or when an ideator's prior ideation participation is high. Our supplementary study further offers preliminary insights on the extension of our proposed effects to the ultimate success of adopted ideas. These findings illuminate a better understanding of firms' idea adoption decisions and suggest ways to manage idea crowdsourcing effectively for new product/service development and improvements.
- Published
- 2018
9. Ideator Expertise and Cocreator Inputs in Crowdsourcing-Based New Product Development
- Author
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Michelle Andrews, John Jianjun Zhu, and Stella Yiyan Li
- Subjects
Knowledge management ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) ,business.industry ,Computer science ,Strategy and Management ,05 social sciences ,Perspective (graphical) ,Novelty ,Crowdsourcing ,Bridge (nautical) ,Knowledge sharing ,Crowds ,Management of Technology and Innovation ,0502 economics and business ,New product development ,050211 marketing ,Product (category theory) ,Marketing ,business ,050203 business & management - Abstract
Crowdsourcing-based new product development (NPD) involves consumers in contributing ideas as ideators in the ideation phase, and providing inputs as cocreators in self-selected subtasks in the product development phase. The novelty of this NPD approach furnishes little understanding about the effect of crowds' self-select participation into ideation and development subtasks, and this study aims to bridge this gap. This article draws on the attention allocation perspective of online knowledge sharing to identify the domains of ideator expertise based on the types of development subtasks they self-selected to perform as cocreators in prior projects. It separately examines the impact of different domains of ideator expertise (marketing and engineering) and the interaction between ideators' expertise and cocreators' inputs on crowdsourcing-based NPD outcomes. Large-scale, longitudinal data from a crowdsourcing-based NPD platform reveal that ideators' engineering expertise helps convert ideas into final products more than ideators' marketing expertise. In contrast, ideators' marketing expertise helps these products achieve more sales than ideators' engineering expertise. Moreover, final products achieve more sales if ideators' marketing expertise embedded in initial product ideas is later augmented with either marketing or engineering-related development inputs by crowd cocreators. However, ideas generated by ideators with engineering expertise achieve fewer product sales when those ideas are complemented by more marketing-related development inputs by cocreators. These findings extend crowdsourcing-based NPD theory and furnish insight on managing crowdsourcing-based NPD platforms.
- Published
- 2017
10. Fostering Customer Ideation in Crowdsourcing Community: The Role of Peer-to-peer and Peer-to-firm Interactions
- Author
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Kimmy Wa Chan, Stella Yiyan Li, and John Jianjun Zhu
- Subjects
Marketing ,Social network ,business.industry ,Perspective (graphical) ,Ideation ,Peer-to-peer ,Public relations ,computer.software_genre ,Crowdsourcing ,Competitive advantage ,Social relation ,Wisdom of the crowd ,Business and International Management ,business ,Psychology ,computer - Abstract
Firms increasingly engage customers in idea generation (or ideation) to sustain their competitive advantages. Drawing from social interaction literature, this study adopts a social network perspective to investigate empirically how the characteristics (i.e., direction, size, and strength) of customers' online peer-to-peer (P2P) and peer-to-firm (P2F) interactions, moderated by customers' past efforts to post ideas (i.e., past ideation participation), influence their likelihood of generating ideas in an idea crowdsourcing community. With four years of data from a popular online crowdsourcing site, this study demonstrates the significant impacts of P2P and P2F online interactions on customers' likelihood of subsequent idea generation. In particular, a potential double-edged sword of past ideation participation emerges: A high level of past ideation participation strengthens (weakens) the impact of P2F (P2P) interactions on customers' subsequent idea generation. These findings suggest implications for how firms can cultivate customers' online social interactions with peers and firms and enhance their capabilities for capturing the wisdom of the crowd.
- Published
- 2015
11. Ideator Expertise and Cocreator Inputs in Crowdsourcing-Based New Product Development
- Author
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John Jianjun Zhu, Michelle Andrews, and Stella Yiyan Li
- Subjects
Knowledge management ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) ,business.industry ,Computer science ,Longitudinal data ,Knowledge integration ,New product development ,Product (category theory) ,Ideation ,business ,Crowdsourcing - Abstract
Crowdsourcing-based new product development (NPD) involves consumers in both the ideation and product development phases. The success of crowdsourcing-based NPD depends on both the ideators’ expertise and the interplay of their expertise with other cocreators’ inputs due to knowledge integration. Large-scale, longitudinal data from a crowdsourcing-based NPD platform reveal that ideators’ engineering expertise helps convert ideas into final products more than ideators’ marketing expertise. In contrast, ideators’ marketing expertise helps these products achieve more sales than ideators’ engineering expertise. Moreover, final products achieve more sales if ideators’ marketing expertise embedded in initial product ideas is later augmented with either marketing or engineering-related development inputs by crowd cocreators. However, ideas generated by ideators with engineering expertise achieve fewer product sales when those ideas are complemented by more marketing-related development inputs by cocreators. These findings extend crowdsourcing-based NPD theory and furnish insight on managing crowdsourcing-based NPD platforms.
- Published
- 2017
12. The elusive engram: what can infantile amnesia tell us about memory?
- Author
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Bridget L. Callaghan, Rick Richardson, and Stella Yiyan Li
- Subjects
Forgetting ,Memory ,General Neuroscience ,Infant, Newborn ,Animals ,Brain ,Humans ,Infant ,Engram ,Psychology ,Neuroscience ,Childhood amnesia - Abstract
Revealing the engram is one of the greatest challenges in neuroscience. Many researchers focus on understanding the cellular and molecular mechanisms underlying the formation and maintenance of the engram, but an underutilized approach has been to investigate analogous processes associated with forgetting. Infant rodents present an ideal model for this purpose because they display a rapid form of non-pathological forgetting known as infantile amnesia (IA). Despite the widespread importance of this interesting phenomenon, the study of the neural bases of IA has remained largely neglected. Here, we consider what IA can tell us about memory. We argue that to understand the mechanisms underlying the engram we must also gain an appreciation of the mechanisms that drive forgetting.
- Published
- 2014
13. An exploration of the HRM values of Chinese managers working in Western multinational enterprises in China: implications for HR practice
- Author
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Stella Yiyan Li and Paul Nesbit
- Subjects
Organizational Behavior and Human Resource Management ,Harmony (color) ,business.industry ,Strategy and Management ,Best practice ,Collectivism ,Accounting ,Individualism ,Multinational corporation ,Management of Technology and Innovation ,Human resource management ,Industrial relations ,Repertory grid ,Sociology ,Business and International Management ,Marketing ,China ,business - Abstract
This paper qualitatively explores the nature of human resource management (HRM) values of local Chinese managers working in Western-based multinational enterprises in China and also considers how these values are associated with preferences for HR practices. The study involves the use of repertory grid interviews with 36 local Chinese managers. The study shows that interviewees reflected a high level of assimilation and internalization of many Western HRM values. Interviewees also retained many traditional Chinese values, thus highlighting the role of institutional and cultural forces on HRM. However, among these local managers, there was clear decline in some traditional Chinese values, such as ‘harmony’ and ‘virtue’. A further interesting finding was the co-existence of paradoxical values of collectivism and individualism among the managers. Analyses of repertory grid data and interview comments also highlight that preferences for HR practices is associated with these underlying HRM values.
- Published
- 2013
14. Estradiol is associated with altered cognitive and physiological responses during fear conditioning and extinction in healthy and spider phobic women
- Author
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Bronwyn M. Graham and Stella Yiyan Li
- Subjects
medicine.medical_treatment ,Exposure therapy ,Conditioning, Classical ,Physiology ,Arousal ,Extinction, Psychological ,03 medical and health sciences ,Behavioral Neuroscience ,Young Adult ,0302 clinical medicine ,Medicine ,Animals ,Humans ,Fear conditioning ,Valence (psychology) ,Communication ,Recall ,Estradiol ,business.industry ,Cognition ,Spiders ,Fear ,Galvanic Skin Response ,Anxiety Disorders ,3. Good health ,030227 psychiatry ,Mental Recall ,Conditioning ,Anxiety ,Female ,medicine.symptom ,Cues ,business ,Cognition Disorders ,030217 neurology & neurosurgery - Abstract
The first-line psychological treatment for anxiety disorders is exposure therapy, which can be modeled in the laboratory using fear extinction. In healthy women, estradiol levels predict return of fear following extinction, whereas low levels are associated with greater return of fear. Investigating whether estradiol is similarly associated with extinction in clinically anxious women may provide insight to mechanisms underlying symptom relapse following exposure therapy. In the present study, women with spider phobia and healthy women participated in a 2-day fear conditioning and extinction procedure during a period of high or low estradiol levels. Skin conductance responses, shock expectancy, and valence ratings were measured throughout. Women exhibited comparable decreases in physiological arousal from conditioning to the end of extinction training on Day 1. However, compared to women with high estradiol, and irrespective of clinical status, women with low estradiol exhibited significant return of physiological arousal at extinction recall on Day 2, despite accurate ratings regarding the likelihood of shock. Low estradiol women also reported heightened threat expectancy and physiological responding during presentation of safety cues. These results may point to novel means of enhancing exposure therapy in women by timing treatment delivery during periods of higher estradiol levels. (PsycINFO Database Record
- Published
- 2016
15. Interpersonal Trust and Platform Credibility in a Chinese Multibrand Online Community
- Author
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Stella Yiyan Li, Kineta Hung, and David K. Tse
- Subjects
Marketing ,Value (ethics) ,Consumption (economics) ,Communication ,media_common.quotation_subject ,Source credibility ,Advertising ,Interpersonal communication ,Online community ,New media ,Credibility ,Quality (business) ,Business ,Business and International Management ,media_common - Abstract
Online communities offer attractive opportunities and challenges to advertisers. Using a revised source credibility framework, this study proposes that interpersonal trust and platform credibility are core to consumer search and consumption behaviors that allow advertisers to harvest value from online communities. We postulate that (1) quality Web features, and user instrumental and relational need fulfillment are antecedents of interpersonal trust and platform credibility; (2) interpersonal trust is distinct from, and an important driver of, platform credibility; and (3) both constructs drive a user's online community usage and brand variety seeking behavior. An online survey of 899 consumers in China supports these propositions and offers both research and managerial implications for this new media platform.
- Published
- 2011
16. Understanding consumer-to-consumer interactions in virtual communities: The salience of reciprocity
- Author
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Stella Yiyan Li and Kimmy Wa Chan
- Subjects
Marketing ,Netnography ,business.industry ,Norm of reciprocity ,Public relations ,Experiential learning ,Explication ,Interactivity ,Social system ,Reciprocity (network science) ,business ,Psychology ,Social psychology ,Virtual community - Abstract
Virtual communities (VCs) represent popular social environments in which people interact by exchanging resources such as information, ideas, and advice about their common interests. Existing research lacks an explication of why people help others in VCs and how such voluntary behaviors drive subsequent attitudes (VC commitment) and behavioral intentions (online co-shopping). This article adopts resource exchange theory to examine how two routes of interactivity (structural vs. experiential) influence reciprocity and affect commitment and co-shopping. Using a netnography study and an online survey, the authors confirm the significant effects of structural and experiential routes of interactivity on reciprocity. Reciprocity has critical effects on social system maintenance by enhancing commitment to the community and intention to co-shop. The results also identify partially mediated relationships among various variables, which suggest that the effects of the experiential route on VC commitment and co-shopping operate partly through reciprocity.
- Published
- 2010
17. A comprehensive study of silicone-based cosmetic textile agent
- Author
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K.K.L. Cheuk, Chi Wai Kan, Johnny Cheuk On Tang, C.W.M. Yuen, Stella Yiyan Li, and S. Y. Cheng
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Skin care ,Textile ,Materials science ,Polymers and Plastics ,business.industry ,General Chemical Engineering ,Thin layer ,General Chemistry ,Biological safety ,chemistry.chemical_compound ,Silicone ,Characterization methods ,chemistry ,Evaluation methods ,Skin structure ,Biochemical engineering ,Composite material ,business - Abstract
In recent years, textile materials have also found applications in the cosmetic field as more and more commercial cosmetic textile agents are now available in the market. In this paper, one commercially available cosmetic textile agent (CTA) for skin caring benefits was used for making the cosmetic textiles. Systematic characterization methods were established to assess their performance in terms of material identification, fabric performance properties as well as biological safety and biological response to human skin. The experimental results showed that after the treatment of cosmetic textile agent, the fiber surface was covered with a thin layer of smooth material, thereby contributing several alterations to fabric properties and providing a better hand feel to human body. The durability of cosmetic textile was considerably satisfactory with respect to the abrasion resistance and washing cycles. The experimental results also illustrated that the cosmetic textiles might probably enhance the replacement of cells with the newly regenerated ones in the skin structure of human body, and thus provided a more efficient turning-over and replacement of skin components.
- Published
- 2009
18. The Influence of eWOM on Virtual Consumer Communities: Social Capital, Consumer Learning, and Behavioral Outcomes
- Author
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Stella Yiyan Li and Kineta Hung
- Subjects
Marketing ,Persuasion ,Communication ,media_common.quotation_subject ,Word of mouth ,Advertising ,Context (language use) ,Reflexivity ,Beauty ,Product (category theory) ,Psychology ,Virtual community ,media_common ,Social capital - Abstract
Word of mouth (WOM) is a highly credible form of marketing information. However, because it is difficult to study WOM in the face-to-face context, researchers have limited understanding of its sources of effectiveness or its effects beyond product and brand communications. We analyzed computer-mediated data and conducted face-to-face interviews with beauty product enthusiasts in China to understand electronic WOM (eWOM) in a consumption-interest virtual community. Our findings reveal four categories of responses: (1) sources of social capital, (2) brand choice facilitation, (3) persuasion knowledge development, and (4) consumer reflexivity. We then propose a model and offer a set of postulates to outline future research directions.
- Published
- 2007
19. Conflict resolution in Chinese family purchase decisions
- Author
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Maggie Chuoyan Dong and Stella Yiyan Li
- Subjects
Marriage Duration ,Strategy and Management ,Communication ,media_common.quotation_subject ,Differential effects ,Conflict resolution strategy ,Orientation (mental) ,Management of Technology and Innovation ,Conflict resolution ,Happiness ,Chinese family ,China ,Psychology ,Social psychology ,media_common - Abstract
PurposeThe purpose of this article is to investigate the impact of Chinese women's changing roles (traditional and modern) and perceived marital happiness on their adoption of different conflict resolution strategies in family purchase decision making (FPDM). It also explores how the relationships vary for women whose marriages have short and long durations.Design/methodology/approachThe paper is framed by and builds on literature on conflict resolution strategies and female role orientation (FRO) in FPDM. Data for this study come from a survey with 735 married Chinese women.FindingsThe paper demonstrates that traditional and modern FRO have differential effects on the adoption of conflict resolution strategies, and the relationships are significantly moderated by marriage duration.Research limitations/implicationsIt sheds light on the changing female roles and marital happiness on conflict resolution in FPDM in China, a society with a centuries‐old traditional culture as well as rapid developments in societal and economic modernization. Future research should investigate more conflict resolution strategies and from both husbands' and wives' perspectives.Practical implicationsThe paper notes the importance of understanding the family structure of a target market. Product designs, advertising, promotions, and even salespeople should be more attentive to the family member who has greater power in FPDM.Originality/valueThe paper shows that traditional and modern FRO have compatible rather than opposite impacts on the adoption of passive and active conflict resolution strategies in FPDM, and the influences change along with increasing marriage duration and it is of value to international marketers.
- Published
- 2007
20. Glocal understandings: female readers’ perceptions of the new woman in Chinese advertising
- Author
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Kineta Hung, Russell W. Belk, and Stella Yiyan Li
- Subjects
Typology ,Economics and Econometrics ,Glocalization ,Strategy and Management ,media_common.quotation_subject ,Organizational culture ,Advertising ,International business ,General Business, Management and Accounting ,Creolization ,Globalization ,Content analysis ,Management of Technology and Innovation ,Reading (process) ,Economics ,Business and International Management ,media_common - Abstract
Research in international advertising has often taken a dichotomized approach, as exemplified by the global standardization vs localization debate. It is assumed under the standardization approach that the globalization process will absorb different national cultures into a global commercial culture, such that standardized advertising should be preferred. The current research argues that the dichotomization approach may have oversimplified the way consumers read and interpret ad images. We postulate that consumers in a transitional economy apply a variety of reading approaches, including different cultural interpretive strategies and self-referencing, to absorb global images into their cultural and consumption schemas. This is commonly referred to as glocalization. We developed a typology of modern women images in Chinese magazine advertising, potential interpretive strategies, and self-referencing responses in this research. Results of a content analysis and a reader response study support our postulations. Implications are discussed. Journal of International Business Studies (2007) 38, 1034–1051. doi:10.1057/palgrave.jibs.8400303
- Published
- 2007
21. Images of the Contemporary Woman in Advertising in China
- Author
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Kineta Hung and Stella Yiyan Li
- Subjects
Marketing ,History ,Content analysis ,Ethnic group ,Gender studies ,Advertising ,Standard of living ,China ,Management Information Systems - Abstract
With changing social expectations, rising living standards, and increasing Western influences in China, young Chinese women residing in urban areas have developed an awareness of their new identities as contemporary women distinct from the traditional or revolutionary ideals of the past. The current study examines the images of women depicted in a representative sample of magazine advertising in China. Of the 427 magazine ads examined, over 80% featured one or more images of contemporary Chinese woman: nurturer (8%), strong woman (12%), flower vase (28%), and urban sophisticate (44%). Further, the findings showed specific correlations between the featured images and (1) product categories, (2) magazine type, and (3) presenter ethnicity. Implications of the findings are discussed.
- Published
- 2006
22. Distinguishing the effect of crystal-field screening from the effect of valence recharging on the 2p3/2 and 3d5/2 level energies of nanostructured copper
- Author
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Chang Q. Sun, Likun Pan, Tupei Chen, Chang Ming Li, Stella Yiyan Li, and Xiao Wei Sun
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Valence (chemistry) ,Passivation ,Binding energy ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Electron ,Condensed Matter Physics ,Copper ,Spectral line ,Surfaces, Coatings and Films ,Auger ,chemistry ,Transition metal ,Atomic physics - Abstract
Incorporating the recent bond order–length–strength correlation mechanism [C.Q. Sun, Phys. Rev. B 69 (2004) 045105] to the size dependence of Auger photoelectron coincidence spectra of Cu nanoparticles with and without being passivated has enabled us to gain quantitative information about the 2p and 3d level energies of an isolated Cu atom and their shift upon bulk formation. The developed approach also enabled us to discriminate the effect of crystal-field screening from the effect of valence recharging (due to surface passivation and substrate–particle interaction) on the binding energies to the electrons at different energy levels of a specimen.
- Published
- 2006
23. Post-stress interface trap generation induced by oxide-field stress with FN injection
- Author
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Stella Yiyan Li, Tupei Chen, Steve Fung, K.F. Lo, and C. D. Beling
- Subjects
Materials science ,Field (physics) ,business.industry ,Transistor ,Analytical chemistry ,Oxide ,Electronic, Optical and Magnetic Materials ,law.invention ,Trap (computing) ,Stress (mechanics) ,Charge pumping ,chemistry.chemical_compound ,chemistry ,law ,MOSFET ,Optoelectronics ,Electrical and Electronic Engineering ,business ,NMOS logic - Abstract
Interface trap generation in nMOS transistors during both stressing and post-stress periods under the conditions of oxide field (dynamic and dc) stress with FN injection is investigated with charge pumping technique. In contrast to the post-stress interface trap generation induced by hot carrier stress which is a logarithmical function of post-stress time, the post-stress interface trap generation induced by oxide-field stress with FN injection first increases with post-stress time but then becomes saturated. The mechanisms for the interface trap generation in both stressing and post-stress periods are described.
- Published
- 1998
24. Interface trap generation by FN injection under dynamic oxide field stress
- Author
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Stevenson Hon Yuen Fung, K.F. Lo, Stella Yiyan Li, and Tupei Chen
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Hydrogen ,Oxide ,chemistry.chemical_element ,Electron ,Electronic, Optical and Magnetic Materials ,Stress (mechanics) ,Trap (computing) ,chemistry.chemical_compound ,chemistry ,MOSFET ,Electrical and Electronic Engineering ,Atomic physics ,Quantum tunnelling ,Voltage - Abstract
Interface trap generation under dynamic (bipolar and unipolar) and dc oxide field stress has been investigated with the charge pumping technique. It is observed that regardless of stress type, whether dc or dynamic (bipolar or unipolar), and the polarity of stress voltage, interface trap generation starts to occur at the voltage at which Fowler-Nordheim (FN) tunneling through the oxide starts to build up. For positive voltage, interface trap generation is attributed to the recombination of trapped holes with electrons and to the bond breaking by the hydrogen (H and H/sup +/) released during stressing. For negative voltage, in addition to these two mechanisms, the bond breaking by energetic electrons may also contribute to interface trap generation. The frequency dependence of interface trap generation is also investigated. Interface trap generation is independent of stressing frequency for unipolar stress but it shows a frequency dependence for bipolar stress.
- Published
- 1998
25. From resilience to vulnerability: mechanistic insights into the effects of stress on transitions in critical period plasticity
- Author
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Bronwyn M. Graham, Rick Richardson, Bridget L. Callaghan, and Stella Yiyan Li
- Subjects
lcsh:RC435-571 ,FGF2 ,media_common.quotation_subject ,maternal-separation ,Review Article ,Childhood amnesia ,Developmental psychology ,lcsh:Psychiatry ,medicine ,Fear conditioning ,Closure (psychology) ,development ,media_common ,Fear processing in the brain ,Psychiatry ,extinction ,Extinction (psychology) ,memory retention ,Mental health ,fear conditioning ,infant ,critical period ,Psychiatry and Mental health ,Anxiety ,Psychological resilience ,medicine.symptom ,Psychology - Abstract
While early experiences are proposed to be important for the emergence of anxiety and other mental health problems, there is little empirical research examining the impact of such experiences on the development of emotional learning. Of the research that has been performed in this area, however, a complex picture has emerged in which the maturation of emotion circuits is influenced by the early experiences of the animal. For example, under typical laboratory rearing conditions infant rats rapidly forget learned fear associations (infantile amnesia) and express a form of extinction learning which is relapse-resistant (i.e., extinction in infant rats may be due to fear erasure). In contrast, adult rats exhibit very long-lasting memories of past learned fear associations, and express a form of extinction learning that is relapse-prone (i.e., the fear returns in a number of situations). However, when rats are reared under stressful conditions then they exhibit adult-like fear retention and extinction behaviours at an earlier stage of development (i.e., good retention of learned fear and relapse-prone extinction learning). In other words, under typical rearing conditions infant rats appear to be protected from exhibiting anxiety whereas after adverse rearing fear learning appears to make those infants more vulnerable to the later development of anxiety. While the effects of different experiences on infant rats’ fear retention and extinction are becoming better documented, the mechanisms which mediate the early transition seen following stress remain unclear. Here we suggest that rearing stress may lead to an early maturation of the molecular and cellular signals shown to be involved in the closure of critical period plasticity in sensory modalities (e.g., maturation of GABAergic neurons, development of perineuronal nets), and speculate that these signals could be manipulated in adulthood to re-open infant forms of emotional learning (i.e., those that favour resilience).
- Published
- 2013
26. Traces of memory: reacquisition of fear following forgetting is NMDAr-independent
- Author
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Stella Yiyan Li and Rick Richardson
- Subjects
Male ,Fear memory ,Time Factors ,Cognitive Neuroscience ,Overt behavior ,Conditioning, Classical ,Stimulus (physiology) ,Receptors, N-Methyl-D-Aspartate ,Extinction, Psychological ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,Conditioning, Psychological ,Animals ,Freezing Reaction, Cataleptic ,Forgetting ,Retention, Psychology ,Fear ,Rats ,Neuropsychology and Physiological Psychology ,NMDA receptor ,Conditioning ,Female ,Dizocilpine Maleate ,Psychology ,Excitatory Amino Acid Antagonists ,psychological phenomena and processes ,Cognitive psychology - Abstract
Recent research shows that while initial learning is dependent on N-methyl-D-aspartate receptors (NMDArs), relearning can be NMDAr-independent. In the present study we examined whether this switch also occurs following forgetting. The developing animal exhibits much more rapid rates of forgetting than adults, so infant rats were used. It was found that infant rats required NMDArs to learn fear (Experiment 1), and that this memory was forgotten after 14 d (Experiment 2). Despite forgetting, relearning fear did not require NMDAr activation (Experiment 3), even if it occurred in adulthood (Experiment 5). Importantly, animals only showed NMDAr-independent reacquisition if they had received paired (white noise–shock) training during conditioning and not if they received unpaired presentations of the white noise and shock (Experiment 4). In addition, this transition following forgetting was not stimulus specific as learning about a novel stimulus (i.e., light, Experiment 6) was also NMDAr-independent. However, reacquisition to a novel stimulus was NMDAr-dependent if the original fear memory was retained at the time of retraining (Experiment 7). Taken together, these results demonstrate how fear memories acquired early in life can have a long-lasting impact on later learning, even when they have been apparently forgotten (i.e., they are not expressed in the animal’s overt behavior). Further, they support the idea that while memories may be forgotten, they are not gone.
- Published
- 2013
27. Updating memories: changing the involvement of the prelimbic cortex in the expression of an infant fear memory
- Author
-
Rick Richardson, Stella Yiyan Li, and Jee Hyun Kim
- Subjects
Male ,Fear memory ,Reflex, Startle ,Memory, Episodic ,Infralimbic cortex ,Prefrontal Cortex ,Rats, Sprague-Dawley ,Memory ,medicine ,Biological neural network ,Limbic System ,Animals ,Postnatal day ,GABA Agonists ,Fear processing in the brain ,Analysis of Variance ,Behavior, Animal ,Muscimol ,General Neuroscience ,Extinction (psychology) ,Fear ,Electric Stimulation ,Rats ,medicine.anatomical_structure ,Expression (architecture) ,Acoustic Stimulation ,Conditioning, Operant ,Psychology ,Neuroscience ,Basolateral amygdala - Abstract
Recent work has found that infant rats (postnatal day (P) 18) do not require the prelimbic cortex (PL) to express learned fear, whereas older animals (adults and juveniles) do. In other words, there is a switch from a PL-independent fear expression system during infancy to a PL-dependent system later in life. The present study investigated whether the PL would be involved in fear expression in rats trained at P17 but tested at P23 (that is, as juveniles). The first two experiments showed that PL involvement in fear expression was determined by the age of the animal at the time of training rather than the animal’s age at the time of test. More specifically, experiment 1 showed that expression of learned fear (measured by freezing, and elicited by a white noise previously paired with a shock) was PL-independent for memories that were acquired when the rat was P17 but then tested at P23. In experiment 2, rats trained at P23, when the PL is functionally mature, still required the PL to express fear when tested at P37. In the last experiment, using two different reactivation procedures, we showed that it is possible to update an infant memory and switch it from being PL-independent to being PL-dependent. Combined, these results have important implications for our understanding of the neural circuitry underlying fear expression across development and show that, at least in some cases, expression of fear responses learned early in life remain PL-independent even as the animal matures.
- Published
- 2012
28. Differential involvement of the medial prefrontal cortex in the expression of learned fear across development
- Author
-
Rick Richardson, Jee Hyun Kim, and Stella Yiyan Li
- Subjects
Male ,Infralimbic cortex ,Conditioning, Classical ,Prefrontal Cortex ,Periaqueductal gray ,Rats, Sprague-Dawley ,03 medical and health sciences ,Behavioral Neuroscience ,chemistry.chemical_compound ,0302 clinical medicine ,Cortex (anatomy) ,medicine ,Animals ,GABA-A Receptor Agonists ,Phosphorylation ,Prefrontal cortex ,Freezing Reaction, Cataleptic ,030304 developmental biology ,Fear processing in the brain ,Neurons ,0303 health sciences ,Muscimol ,Extinction (psychology) ,Fear ,Rats ,medicine.anatomical_structure ,chemistry ,Mitogen-Activated Protein Kinases ,Psychology ,Neuroscience ,030217 neurology & neurosurgery ,Basolateral amygdala - Abstract
Studies have shown that in adult animals the medial prefrontal cortex (mPFC) is a critical brain region involved in fear regulation, with the prelimbic (PL) subregion being important for fear expression. However, few studies have examined whether the PL cortex is also involved in fear expression in infant animals. Five experiments, using immunohistochemical and temporary inactivation procedures, assessed the role of the PL in the expression of learned fear in postnatal day (PND) 18 (infant) and PND25 (juvenile) rats. We found that in juvenile rats expressing fear (measured through freezing) there was an increase in the number of phosphorylated mitogen-activated protein kinase (pMAPK)-labeled neurons in the PL; this increase was not observed in the infralimbic cortex. Furthermore, inactivation of the PL at test, using muscimol, decreased freezing in the juvenile rat. In contrast, expression of learned fear in infant rats did not require the PL, as there was neither an increase in the number of pMAPK-labeled cells in the PL nor was there any effect of PL inactivation on freezing levels. Taken together, these experiments suggest that a different neural circuitry underlies fear regulation early in life and that the lack of mPFC involvement may reflect a less flexible emotional regulation system in infant animals.
- Published
- 2012
29. Phosphorylation of mitogen-activated protein kinase in the medial prefrontal cortex and the amygdala following memory retrieval or forgetting in developing rats
- Author
-
Gavan P. McNally, Rick Richardson, Jee Hyun Kim, Adam S. Hamlin, and Stella Yiyan Li
- Subjects
MAPK/ERK pathway ,Male ,Cognitive Neuroscience ,Conditioning, Classical ,Prefrontal Cortex ,Experimental and Cognitive Psychology ,Amygdala ,Extinction, Psychological ,Rats, Sprague-Dawley ,Behavioral Neuroscience ,Memory ,medicine ,Animals ,Phosphorylation ,Prefrontal cortex ,Protein kinase A ,Neurons ,Forgetting ,biology ,Fear ,Rats ,medicine.anatomical_structure ,nervous system ,Mitogen-activated protein kinase ,biology.protein ,Immunohistochemistry ,Mitogen-Activated Protein Kinases ,Psychology ,Neuroscience - Abstract
We examined neuronal correlates of forgetting in rats by detection of phosphorylated mitogen-activated protein kinase (pMAPK) in the medial prefrontal cortex (mPFC) and amygdala. In Experiment 1, postnatal day (P)23 and P16 rats received paired noise CS-shock US presentations. When tested immediately after conditioning, P23 and P16 rats exhibited similar levels of conditioned fear; when tested after 2 days, however, P16 rats showed poor CS-elicited freezing relative to P23 rats. In Experiment 2, P16 and P23 rats received either paired or unpaired CS-US presentations, and then were tested 48 h later. Consistent with Experiment 1, P16 rats showed forgetting whereas P23 rats exhibited good retention at test. Additionally, unpaired groups showed poor CS-elicited freezing at test. Immunohistochemistry showed that P23 and P16 rats given paired presentations exhibited significant elevation of pMAPK-immunoreactive (ir) neurons in the amygdala compared to rats given unpaired presentations. That is, MAPK phosphorylation in the amygdala tracked learning history rather than behavioral performance at test. In contrast, only the P23-paired group showed an elevated number of pMAPK-ir neurons in mPFC, indicating that MAPK phosphorylation in the mPFC tracks memory expression. Different test-perfusion intervals were employed in Experiment 3, which showed that the developmental dissociation in the pMAPK-ir neurons observed in the mPFC in Experiment 2 was not due to age differences in the rate of phosphorylation of MAPK. These findings provide initial evidence suggesting that while the mPFC is involved in memory retrieval, MAPK phosphorylation in the amygdala may be a persisting neural signature of fear memory.
- Published
- 2011
30. Changes in the Positron-Electron Momentum Distribution in GaAs Brought about by Chopped Light
- Author
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C. D. Beling, Chi Chung Ling, Steve Fung, and Stella Yiyan Li
- Subjects
Antiparticle ,Momentum (technical analysis) ,Annihilation ,Materials science ,business.industry ,Mechanical Engineering ,Electron ,Condensed Matter Physics ,Electromagnetic radiation ,Optics ,Positron ,Mechanics of Materials ,General Materials Science ,Atomic physics ,business ,Lepton ,Doppler broadening - Published
- 2001
31. Immunohistochemical analyses of long-term extinction of conditioned fear in adolescent rats
- Author
-
Jee Hyun Kim, Stella Yiyan Li, and Rick Richardson
- Subjects
Male ,medicine.medical_specialty ,Cognitive Neuroscience ,Infralimbic cortex ,Conditioning, Classical ,Poison control ,Prefrontal Cortex ,P70-S6 Kinase 1 ,Amygdala ,Developmental psychology ,Extinction, Psychological ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,Internal medicine ,medicine ,Animals ,Phosphorylation ,Prefrontal cortex ,Mitogen-Activated Protein Kinase Kinases ,Age Factors ,Classical conditioning ,Extinction (psychology) ,Fear ,Immunohistochemistry ,Rats ,medicine.anatomical_structure ,Endocrinology ,Anxiety ,medicine.symptom ,Psychology - Abstract
Adolescence is a period of heightened emotional reactivity and vulnerability to poor outcomes (e.g., suicide, anxiety, and depression). Recent human and animal neuroimaging studies suggest that dramatic changes in prefrontal cortical areas during adolescence are involved in these effects. The present study explored the functional implications of prefrontal cortical changes during adolescence by examining conditioned fear extinction in adolescent rats. Experiment 1 showed that preadolescent (i.e., postnatal day [P] 24), adolescent (P35), and adult (P70) rats express identical extinction acquisition following 3 white-noise conditioned stimulus (CS) and shock pairings. When tested the next day, however, adolescent rats showed almost complete failure to maintain extinction of CS-elicited freezing compared with P24 and P70 rats. It was observed in experiment 2 that following extinction, P24 and P70 rats express significantly elevated levels of phosphorylated mitogen-activated protein kinase (pMAPK) in the infralimbic cortex (IL) compared with adolescent rats. Interestingly, adolescent rats successfully exhibited long-term extinction if the amount of extinction training was doubled (experiment 3). More extinction training also led to increased phosphorylation of MAPK in the IL in these rats. These findings suggest that adolescents are less efficient in utilizing prefrontal areas, which may lead to an impairment in the maintenance of extinguished behavior.
- Published
- 2010
32. Room-Temperature Ultraviolet Lasing from Zinc Oxide Microtubes
- Author
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B. J. Chen, Stella Yiyan Li, Chunxiang Xu, Siu Fung Yu, Clement Yuen, and Xiao Wei Sun
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Zinc ,Laser ,medicine.disease_cause ,law.invention ,Laser linewidth ,chemistry ,law ,medicine ,Optoelectronics ,business ,Lasing threshold ,Excitation ,Ultraviolet - Abstract
Prismatic zinc oxide microtubes have been fabricated by vapor transport. Room-temperature ultraviolet lasing action has been demonstrated in these microtube arrays. The ZnO microtubes, mainly appearing in tapped bell-mouthed shape, form natural laser cavities along the length direction. The hexagon diagonal and length of the microtube vary from 1 µm to 20 µm and 10 µm to a few hundred µm respectively. Under 355 nm optical excitation, lasing action is observed at room-temperature around 393 nm. Multi-longitudinal modes are also observed with significantly narrowed emission linewidth.
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