Nouns are more important than other parts of speech in information retrieval and are more often found near the beginning or the end of sentences. In this paper, we investigate the effects of rewarding terms based on their location in sentences on information retrieval. Particularly, we propose a novel Term Location (TEL) retrieval model based on BM25 to enhance probabilistic information retrieval, where a kernel-based method is used to capture term placement patterns. Experiments on five TREC datasets of varied size and content indicate the proposed model significantly outperforms the optimized BM25 and DirichletLM in MAP over all datasets with all kernel functions, and excels the optimized BM25 and DirichletLM over most of the datasets in [email protected] and [email protected] with different kernel functions.

Influenza poses a significant risk to public health, as evident by the 2009 H1N1 pandemic. Hospital emergency departments monitor infectious diseases such as influenza with surveillance systems based on arriving chief complaints. However, existing systems are too reliant on the completeness of data and are not acceptably accurate in a practical setting. To improve prediction accuracy, we propose a data cleaning process for data collected in hospital settings. Besides, we also propose a novel feature selection method called the Importance Contribution Index (ICI) which is based on orthogonal transformation. Various feature selection and pattern classification approaches are analyzed. The ICI and C4.5 decision tree are eventually adopted in the new surveillance system. Validation results have shown that the total accuracy has been improved by 7.1% in the enhanced system.