 It is an application of Machine Learning that firstly uses Feature Selection to automatically extract flu-related terms from Twitter content and then uses those terms to compute a flu-score for several UK regions based on geolocated tweets.
<clarity>  It is an application of Machine Learning that firstly uses Feature Selection to automatically extract flu-related terms from Twitter content and then uses those terms to compute a flu-score for several UK regions based on geolocated tweets.
 It is an application of machine learning that first used feature selection to automatically extract flu-related terms from Twitter content and then uses those terms to compute a flu-score for several UK regions based on geolocated tweets.