Data Mining Practical Machine Learning Tools and Techniques

We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

Twitter, a microblogging service less than three years old, commands more than 41 million users as of July 2009 and is growing fast. Twitter users tweet about any topic within the 140-character limit and follow others to receive their tweets. The goal of this paper is to study the topological characteristics of Twitter and its power as a new medium of information sharing.We have crawled the entire Twitter site and obtained 41.7 million user profiles, 1.47 billion social relations, 4,262 trending topics, and 106 million tweets. In its follower-following topology analysis we have found a non-power-law follower distribution, a short effective diameter, and low reciprocity, which all mark a deviation from known characteristics of human social networks [28]. In order to identify influentials on Twitter, we have ranked users by the number of followers and by PageRank and found two rankings to be similar. Ranking by retweets differs from the previous two rankings, indicating a gap in influence inferred from the number of followers and that from the popularity of one's tweets. We have analyzed the tweets of top trending topics and reported on their temporal behavior and user participation. We have classified the trending topics based on the active period and the tweets and show that the majority (over 85%) of topics are headline news or persistent news in nature. A closer look at retweets reveals that any retweeted tweet is to reach an average of 1,000 users no matter what the number of followers is of the original tweet. Once retweeted, a tweet gets retweeted almost instantly on next hops, signifying fast diffusion of information after the 1st retweet.To the best of our knowledge this work is the first quantitative study on the entire Twittersphere and information diffusion on it.

https://ink.library.smu.edu.sg/cgi/viewcontent.cgi?article=7104&context=sis_research

What is Twitter, a social network or a news media?

The term “Linked Data” refers to a set of best practices for publishing and connecting structured data on the Web. These best practices have been adopted by an increasing number of data providers over the last three years, leading to the creation of a global data space containing billions of assertions— the Web of Data. In this article, the authors present the concept and technical principles of Linked Data, and situate these within the broader context of related technological developments. They describe progress to date in publishing Linked Data on the Web, review applications that have been developed to exploit the Web of Data, and map out a research agenda for the Linked Data community as it moves forward.

/pdf/linked-data-the-story-so-far-2a9zvmaysa.pdf

Linked Data - the story so far

Obesity now affects one in five children in the United States. Discrimination against overweight children begins early in childhood and becomes progressively institutionalized. Because obese children tend to be taller than their nonoverweight peers, they are apt to be viewed as more mature. The inappropriate expectations that result may have an adverse effect on their socialization. Many of the cardiovascular consequences that characterize adult-onset obesity are preceded by abnormalities that begin in childhood. Hyperlipidemia, hypertension, and abnormal glucose tolerance occur with increased frequency in obese children and adolescents. The relationship of cardiovascular risk factors to visceral fat independent of total body fat remains unclear. Sleep apnea, pseudotumor cerebri, and Blount's disease represent major sources of morbidity for which rapid and sustained weight reduction is essential. Although several periods of increased risk appear in childhood, it is not clear whether obesity with onset early in childhood carries a greater risk of adult morbidity and mortality. Obesity is now the most prevalent nutritional disease of children and adolescents in the United States. Although obesity-associated morbidities occur more frequently in adults, significant consequences of obesity as well as the antecedents of adult disease occur in obese children and adolescents. In this review, I consider the adverse effects of obesity in children and adolescents and attempt to outline areas for future research. I refer to obesity as a body mass index greater than the 95th percentile for children of the same age and gender.

Health Consequences of Obesity in Youth: Childhood Predictors of Adult Disease

Many libraries and databases are closed to general-purpose Web crawlers, and they expose their content only through their own search engines. At the same time many researchers attempt to locate technical papers through general-purpose Web search engines. DP9 is an open source gateway service that allows general search engines, (e.g. Google, Inktomi) to index OAI-compliant archives. DP9 does this by providing consistent URLs for repository records, and converting them to OAI queries against the appropriate repository when the URL is requested. This allows search engines that do not support the OAI protocol to index the "deep Web" contained within OAI compliant repositories.

DP9: an OAI gateway service for web crawlers

IntroductionThe web is in constant flux---new pages and Web sites appear daily, and old pages and sites disappear almost as quickly. One study estimates that about two percent of the Web disappears from its current location every week.2 Although Web users have become accustomed to seeing the infamous "404 Not Found" page, they are more taken aback when they own, are responsible for, or have come to rely on the missing material.Web archivists like those at the Internet Archive have responded to the Web's transience by archiving as much of it as possible, hoping to preserve snapshots of the Web for future generations.3 Search engines have also responded by offering pages that have been cached as a result of the indexing process. These straightforward archiving and caching efforts have been used by the public in unintended ways: individuals and organizations have used them to restore their own lost Web sites.5To automate recovering lost Web sites, we created a Web-repository crawler named Warrick that restores lost resources from the holdings of four Web repositories: Internet Archive, Google, Live Search (now Bing), and Yahoo;6 we refer to these Web repositories collectively as the Web Infrastructure (WI). We call this after-loss recovery Lazy Preservation (see the sidebar for more information). Warrick can only recover what is accessible to the WI, namely the crawlable Web. There are numerous resources that cannot be found in the WI: password protected content, pages without incoming links or protected by the robots exclusion protocol, and content hidden behind Flash or JavaScript interfaces. Most importantly, WI crawlers do not have access to the server-side components (for example, scripts, configuration files, databases, among others) of a Web site.Nevertheless, upon Warrick's public release in 2005, we received many inquiries about its usage and collected a handful of anecdotes about the Web sites individuals and organizations had lost and wanted to recover. Were these Web sites representative? What types of Web resources were people losing? Given the inherent limitations of the WI, were Warrick users recovering enough material to reconstruct the site? Were these losses changing their behavior, or was the availability of cached material reinforcing a "lazy" approach to preservation?We constructed an online survey to explore these questions and conducted a set of in-depth interviews with survey respondents to clarify the results. Potential participants were solicited by us or the Internet Archive, or they found a link to the survey from the Warrick Web site. A total of 52 participants completed the survey regarding 55 lost Web sites, and seven of the participants allowed us to follow-up with telephone or instant messaging interviews. Participants were divided into two groups:1. Personal loss: Those who had lost (and tried to recover) a Web site that they had personally created, maintained or owned (34 participants who lost 37 Web sites).2. Third party: Those who had recovered someone else's lost Web site (18 participants who recovered 18 Web sites).

/pdf/why-web-sites-are-lost-and-how-they-re-sometimes-found-r0m371wd89.pdf

Why web sites are lost (and how they're sometimes found)

With the proliferation of public web archives, it is becoming more important to better profile their contents, both to understand their immense holdings as well as support routing of requests in the Memento aggregator. To save time, the Memento aggregator should only poll the archives that are likely to have a copy of the requested URI. Using the CDX files produced after crawling, we can generate profiles of the archives that summarize their holdings and can be used to inform routing of the Memento aggregator’s URI requests. Previous work in profiling ranged from using full URIs (no false positives, but with large profiles) to using only top-level domains (TLDs) (smaller profiles, but with many false positives). This work explores strategies in between these two extremes. In our experiments, we gained up to 22 % routing precision with less than 5 % relative cost as compared to the complete knowledge profile without any false negatives. With respect to the TLD-only profile, the registered domain profile doubled the routing precision, while complete hostname and one path segment gave a five fold increase in routing precision.

/pdf/web-archive-profiling-through-cdx-summarization-2fww4mh1x7.pdf

Web Archive Profiling Through CDX Summarization

Peripheral artery disease (PAD) is a prevalent condition that confers substantial morbidity and mortality and remains underdiagnosed as well as undertreated in the overall population. Although PAD prevalence is similar or higher in women compared with men, associations of traditional and nontraditional risk factors with PAD and clinical manifestations of PAD differ by sex and may contribute to delayed or lack of diagnosis in women. Such sex-based differences in the manifestation of PAD may arise from sexual dimorphism in the vascular substrate in health as well as sex variation in the responses to vascular stressors. Despite the availability of proven therapies for improving symptoms and reducing risk of ischemic cardiovascular and limb events among patients with diagnosed PAD, important sex differences in treatment and outcomes have been observed. We provide an overview of current knowledge regarding sex differences in the epidemiology, pathophysiology, clinical presentation, and management of PAD.

Sex Differences in Peripheral Artery Disease

Inaccessible Web pages and 404 "Page Not Found" responses are a common Web phenomenon and a detriment to the user's browsing experience. The rediscovery of missing Web pages is, therefore, a relevant research topic in the digital preservation as well as in the Information Retrieval realm. In this article, we bring these two areas together by analyzing four content- and link-based methods to rediscover missing Web pages. We investigate the retrieval performance of the methods individually as well as their combinations and give an insight into how effective these methods are over time. As the main result of this work, we are able to recommend not only the best performing methods but also the sequence in which they should be applied, based on their performance, complexity required to generate them, and evolution over time. Our least complex single method results in a rediscovery rate of almost $$70\,\%$$ 70 % of Web pages of our sample dataset based on URIs sampled from the Open Directory Project (DMOZ). By increasing the complexity level and combining three different methods, our results show an increase of the success rate of up to $$77\,\%$$ 77 % . The results, based on our sample dataset, indicate that Web pages are often not completely lost but have moved to a different location and "just" need to be rediscovered.

/pdf/moved-but-not-gone-an-evaluation-of-real-time-methods-for-4u8rt9aehf.pdf

Michael L. Nelson

Papers

DP9: an OAI gateway service for web crawlers

Why web sites are lost (and how they're sometimes found)

Web Archive Profiling Through CDX Summarization

Sex Differences in Peripheral Artery Disease

Moved but not gone: an evaluation of real-time methods for discovering replacement web pages