You are provided with the abstract of a scientific paper and the abstracts of the papers it references. Your task is to write a Related Work section for the main paper. This section should concisely summarize and integrate the key points from the cited abstracts, reflecting how they relate to the main paper's contributions and context. In your summary, use numerical citation markers like [1], [2], etc., to refer to the corresponding papers.

Main Abstract:
Users of social media sites like Facebook and Twitter rely on crowdsourced content recommendation systems (e.g., Trending Topics) to retrieve important and useful information. Contents selected for recommendation indirectly give the initial users who promoted (by liking or posting) the content an opportunity to propagate their messages to a wider audience. Hence, it is important to understand the demographics of people who make a content worthy of recommendation, and explore whether they are representative of the media site's overall population. In this work, using extensive data collected from Twitter, we make the first attempt to quantify and explore the demographic biases in the crowdsourced recommendations. Our analysis, focusing on the selection of trending topics, finds that a large fraction of trends are promoted by crowds whose demographics are significantly different from the overall Twitter population. More worryingly, we find that certain demographic groups are systematically under-represented among the promoters of the trending topics. To make the demographic biases in Twitter trends more transparent, we developed and deployed a Web-based service 'Who-Makes-Trends' at twitter-app.mpi-sws.org who-makes-trends.

Cited Abstract(s):
[1]: As social media continue to grow, the zeitgeist of society is increasingly found not in the headlines of traditional media institutions, but in the activity of ordinary individuals. The identification of trending topics utilises social media (such as Twitter) to provide an overview of the topics and issues that are currently popular within the online community. In this paper, we outline methodologies of detecting and identifying trending topics from streaming data. Data from Twitter's streaming API was collected and put into documents of equal duration using data collection procedures that allow for analysis over multiple timespans, including those not currently associated with Twitter-identified trending topics. Term frequency-inverse document frequency analysis and relative normalised term frequency analysis were performed on the documents to identify the trending topics. Relative normalised term frequency analysis identified unigrams, bigrams, and trigrams as trending topics, while term frequency-inverse document frequency analysis identified unigrams as trending topics. Application of these methodologies to streaming data resulted in F-measures ranging from 0.1468 to 0.7508.

[2]: We examine the problem of collective attention spam, in which spammers target social media where user attention quickly coalesces and then collectively focuses around a phenomenon. Compared to many existing spam types, collective attention spam relies on the users themselves to seek out the content -- like breaking news, viral videos, and popular memes -- where the spam will be encountered, potentially increasing its effectiveness and reach. We study the presence of collective attention spam in one popular service, Twitter, and we develop spam classifiers to detect spam messages generated by collective attention spammers. Since many instances of collective attention are bursty and unexpected, it is difficult to build spam detectors to pre-screen them before they arise; hence, we examine the effectiveness of quickly learning a classifier based on the first moments of a bursting phenomenon. Through initial experiments over a small set of trending topics on Twitter, we find encouraging results, suggesting that collective attention spam may be identified early in its life cycle and shielded from the view of unsuspecting social media users.

[3]: Twitter summarizes the great deal of messages posted by users in the form of trending topics that reflect the top conversations being discussed at a given moment. These trending topics tend to be connected to current affairs. Different happenings can give rise to the emergence of these trending topics. For instance, a sports event broadcasted on TV, or a viral meme introduced by a community of users. Detecting the type of origin can facilitate information filtering, enhance real-time data processing, and improve user experience. In this paper, we introduce a typology to categorize the triggers that leverage trending topics: news, current events, memes, and commemoratives. We define a set of straightforward language-independent features that rely on the social spread of the trends to discriminate among those types of trending topics. Our method provides an efficient way to immediately and accurately categorize trending topics without need of external data, outperforming a content-based approach.

[4]: Online news media sites are presently the primary sources of news for a large number of users world-wide. The content published by media sites have high temporal churn as they tend to focus on recommending recent breaking news. Analyzing data from a popular online mass media site nytimes.com as well as a popular online social media site twitter.com, we show that the resulting churn in popular content can lead to temporal coverage biases in the stories that are consumed by a user, based on the time of the day when the user accesses the media sites.
Many prior works have focused on Twitter Trending Topics. For example, Zubiaga presented an approach to automatically categorize trending topics [3] . Lee characterized how spammers can exploit trending topics [2] . Benhardus [1] proposed alternative algorithms for detecting trending topics. Our prior work [4] identified temporal coverage biases in the selection of trending stories.