The Lifecycles of Apps in a Social Ecosystem

Apps are emerging as an important form of on-line content, and they combine aspects of Web usage in interesting ways --- they exhibit a rich temporal structure of user adoption and long-term engagement, and they exist in a broader social ecosystem that helps drive these patterns of adoption and engagement. It has been difficult, however, to study apps in their natural setting since this requires a simultaneous analysis of a large set of popular apps and the underlying social network they inhabit. In this work we address this challenge through an analysis of the collection of apps on Facebook Login, developing a novel framework for analyzing both temporal and social properties. At the temporal level, we develop a retention model that represents a user's tendency to return to an app using a very small parameter set. At the social level, we organize the space of apps along two fundamental axes --- popularity and sociality --- and we show how a user's probability of adopting an app depends both on properties of the local network structure and on the match between the user's attributes, his or her friends' attributes, and the dominant attributes within the app's user population. We also develop models that show the importance of different feature sets with strong performance in predicting app success.Comment: 11 pages, 10 figures, 3 tables, International World Wide Web Conferenc

Development and application of an antigen capture ELISA assay for diagnosis of Japanese encephalitis virus in swine, human and mosquito

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis (JE) is a serious zoonosis caused by the Japanese encephalitis virus (JEV) which is a mosquito-borne pathogen of the family <it>Flavivirus</it>. However, the application of several developed laboratory methods for the detection of JEV antigens or antibodies are limited by their requirements of laboratory operations, skilled technicians and special facilities.</p> <p>Results</p> <p>To develop a method for detecting JEV antigen in swine, human, mosquito and other clinical specimens specifically, conveniently and effectively, an antigen capture enzyme-linked immunosorbent assay (ELISA) was established in this study. Sensitivity, specificity, repeatability and stability of the developed method were evaluated, and 60 clinical samples were tested in this study. The results demonstrated that the antigen capture ELISA was capable in detecting JEV antigen with high sensitivity and specificity compared with conventional methods. 14 samples showed the positive result with coincidence rate of 70%, and 46 displayed negative result with coincidence rate of 100% as compared to that of reverse transcription-polymerase chain reaction (RT-PCR).</p> <p>Conclusions</p> <p>The developed ELISA assay provides a convenient and specific method for the large-scale determination of JEV antigen in infected swine, human and mosquito samples with high sensitivity and specificity.</p

Addressing the Accessibility of Social Media

Social media platforms are deeply ingrained in society, and they offer many different spaces for people to engage with others. Unfortunately, accessibility barriers prevent people with disabilities from fully participating in these spaces. Social media users commonly post inaccessible media, including videos without captions (which are important for people who are deaf or hard of hearing) and images without alternative text (descriptions read aloud by screen readers for people who are blind). Users with motor impairments must find workarounds to deal with the complex user interfaces of these platforms, and users with cognitive disabilities may face barriers to composing and sharing information. Accessibility researchers, industry practitioners, and end-users with disabilities will come together to outline challenges and solutions for improving social media accessibility. The workshop starts with a panel of end-users with disabilities who will recount their Perspectives of Successes and Barriers. Industry professionals from social media companies (e.g., Facebook and LinkedIn) will detail their Design Process and Implementation Challenges in a panel with questions from attendees. The attendees will share their work and tackle Open Challenges and Future Research Directions. This workshop will forge collaborations between researchers and practitioners, and define high-priority accessibility challenges for social media platforms

Protection of Visual Functions by Human Neural Progenitors in a Rat Model of Retinal Disease

BACKGROUND: A promising clinical application for stem and progenitor cell transplantation is in rescue therapy for degenerative diseases. This strategy seeks to preserve rather than restore host tissue function by taking advantage of unique properties often displayed by these versatile cells. In studies using different neurodegenerative disease models, transplanted human neural progenitor cells (hNPC) protected dying host neurons within both the brain and spinal cord. Based on these reports, we explored the potential of hNPC transplantation to rescue visual function in an animal model of retinal degeneration, the Royal College of Surgeons rat. METHODOLOGY/PRINCIPAL FINDINGS: Animals received unilateral subretinal injections of hNPC or medium alone at an age preceding major photoreceptor loss. Principal outcomes were quantified using electroretinography, visual acuity measurements and luminance threshold recordings from the superior colliculus. At 90–100 days postnatal, a time point when untreated rats exhibit little or no retinal or visual function, hNPC-treated eyes retained substantial retinal electrical activity and visual field with near-normal visual acuity. Functional efficacy was further enhanced when hNPC were genetically engineered to secrete glial cell line-derived neurotrophic factor. Histological examination at 150 days postnatal showed hNPC had formed a nearly continuous pigmented layer between the neural retina and retinal pigment epithelium, as well as distributed within the inner retina. A concomitant preservation of host cone photoreceptors was also observed. CONCLUSIONS/SIGNIFICANCE: Wild type and genetically modified human neural progenitor cells survive for prolonged periods, migrate extensively, secrete growth factors and rescue visual functions following subretinal transplantation in the Royal College of Surgeons rat. These results underscore the potential therapeutic utility of hNPC in the treatment of retinal degenerative diseases and suggest potential mechanisms underlying their effect in vivo

The Dynamics Of Information Diffusion On On-Line Social Networks

Although there has been a long history of studying the diffusion of information in various social science fields, existing theories are mostly built on direct observations in small networks or survey responses from large samples. As a result, it is hard to verify or refute these theories empirically on a large scale. In recent years, the abundance of digital records of online interactions has provided us for the first time both explicit network structure and detailed dynamics, supporting global-scale, quantitative study of diffusion in the real world. Using these large scale datasets collected from social media sites, we are able to dissect and study the process of information diffusion in its three components: people, information, and network. This thesis mainly addresses a few long-standing questions about each component, including: "who influences whom?", "how do different types of information spread?", and "how does the network structure impact the diffusion process?" In our search of answers for these questions, we realize that these three components are interconnected, constantly interacting with each other in real-world diffusion processes. Thus our results on each component should not be taken in isolation but be viewed interdependently. To understand who influences whom in today's hybrid communication environment, we study people's influence on social media based on their role in the global media ecosystem. By categorizing Twitter accounts into elite (i.e. celebrities, media outlets, organizations, and bloggers) and ordinary users, we find a striking concentration of attention on a minority of elite users, and significant homophily within elite categories. On the other hand, following the definition of "opinion leaders" in the classical "two-step flow" theory, we find a large population of opinion leaders who serve as a layer of intermediaries between the elite users and the masses. The next question we ask is the role of content in the diffusion process. In contrast to previous research on the virality of information, we switch our focus to the persistence of information, trying to understand why certain content keeps on spreading in social media for a long time while most does not. First, we see an interaction effect, from both people and content, on the lifespan of information. As a result, there is a significant difference in lifespan, for information broadcast by different categories of users. Second, we find a strong association between the linguistic style of content and its temporal dynamics: rapidly-fading information contains significantly more words related to negative emotion, actions, and more complicated cognitive processes, whereas persistent information contains more words related to positive emotion, leisure, and lifestyle. In the end, we conduct a longitudinal study of the local and global structure of several large social networks, asking how and where disengagement happens in the social graph. We find that, although there is a significant correlation in both arrival and departure among friends, the dynamics of departure behave differently from the dynamics of arrival. In particular, for the majority of users with a sufficient number (e.g., greater than 20) of friends, departure is best predicted by the overall fraction of active friends within a user's neighborhood, independent of the size of the neighborhood. We also find that active users tend to belong to a core that is densifying and is significantly denser than the inactive users, and the inactive set of users exhibit a higher density and lower conductance than the degree distribution alone can explain. These two aspects suggest that nodes at the fringe are more likely to depart and subsequent departures are correlated among neighboring nodes in tightly-knit communities

Campus Virtual Tour System based on Cylindric Panorama

Abstract Virtual tour is a prominent problem in virtual reality research. In this paper, we review some virtual tour system and propose a project plan of “Virtual tour in Tsinghua University”. The core code and the prototype of the system are completed. Experimental results show that our design is feasible and effective. It can bring the feeling of reality and immersion

Mapping language literacy at scale: a case study on Facebook

Abstract Literacy is one of the most fundamental skills for people to access and navigate today’s digital environment. This work systematically studies the language literacy skills of online populations for more than 160 countries and regions across the world, including many low-resourced countries where official literacy data are particularly sparse. Leveraging public data on Facebook, we develop a population-level literacy estimate for the online population that is based on aggregated and de-identified public posts written by adult Facebook users globally, significantly improving both the coverage and resolution of existing literacy tracking data. We found that, on Facebook, women collectively show higher language literacy than men in many countries, but substantial gaps remain in Africa and Asia. Further, our analysis reveals a considerable regional gap within a country that is associated with multiple socio-technical inequalities, suggesting an “inequality paradox” – where the online language skill disparity interacts with offline socioeconomic inequalities in complex ways. These findings have implications for global women’s empowerment and socioeconomic inequalities