## 8 Visualization of Expertise Profiles  
As described previously, STEP aims at capturing the _temporality_ of expertise by differentiating between _short term_ and _long-term_ profiles. A short-term profile represents a collection of concepts extracted from micro-contributions over a period of time. The goal of the long-term profile, on the other hand, is to capture the collection of concepts occurring both persistently and uniformly across all short-term profiles for an expert. Capturing the temporal aspect of expertise offers significant value as it facilitates tracking and analyzing changes in interests and expertise overtime. In order to provide a user friendly and intuitive _framework_ for the _visualization_ and _analysis_ of _evolving interests and expertise overtime_, we have created the \"_Profile Explorer_\" [18] visualization tool. Profile Explorer facilitates visualization of short term and long term profiles and provides a framework for conducting _comparative analysis_ of experts and expertise by linking an expert's long term profile with short term profiles and underlying contributions. Profile Explorer creates a _paradigm_ that facilitates _visualization, search and comparative analysis_ of expertise profiles. We have specifically de-coupled Profile Explorer from our methodology and the biomedical domain, _i.e._, the domain within which our experiments are conducted, in order to provide a _visualization paradigm_ for analyzing expertise that is _independent of methodology or domain_. Furthermore, visualizing the temporal aspect captured by our expertise model facilitates detailed analysis of interests and expertise by allowing us to determine: (i) the level of activity in particular topics over time; (ii) the burst of activity in particular topics (short term profiles); (iii) the amount of time an expert has been contributing to specific topics; (iv) how recently an expert has made contributions to a specific topic; (v) the most/least active experts in particular topic/s; (vi) if participants' activities are in line with the focus of the project or underlying articles (as concepts in short-term profiles can be linked to terms in micro-contributions through the Fine-grained provenance ontology); (vii) the level of collaboration among authors; e.g., determine the group of authors who have had the highest level of activity in a particular topic over a period of time; (viii) the ontology/s which have best described the contributions to a particular project; _i.e._, viewing a project from the point of view of a particular domain; (ix) the expertise of authors contributing to multiple projects; (x) comparison of expertise captured from contributions to multiple projects. Profile Explorer utilizes _TimelineJS_[30] to demonstrate the _temporal_ aspect of expertise profiles. TimelineJS is a storytelling, user friendly and intuitive timeline built in JavaScript. It can pull in media from different sources and has built in support for Twitter, Flickr, Google Maps, YouTube, Vimeo, Dailymotion, Wikipedia, SoundCloud and more media types in the future. Profile Explorer also utilizes _Data-driven Documents_[_D3_][31] to illustrate the content of expertise profiles (_i.e._, concepts from domain-specific ontologies) as word clouds. Data-driven Documents (D3) is a JavaScript library for binding data to graphics using HTML, SVG and CSS, animation and interaction. The most important features that clearly distinguish Profile Explorer from other expertise visualization tools and networks are (i) capturing and visualizing the _time-dependent_ aspect of expertise; (ii) conducting comparative analysis based on _semantics_ represented by ontological concepts and (iii) the ability to visualize and analyze expertise profiles _independent of domain or methodology_.