Chenwei Zhang

Mining User Intentions from Medical Queries: A Neural Network Based Heterogeneous Jointly Modeling Approach

Text queries are naturally encoded with user intentions. An intention detection task tries to model and discover intentions that user encoded in text queries. Unlike conventional text classification tasks where the label of text is highly correlated with some topic-specific words, words from different topic categories tend to co-occur in medical related queries. Besides the existence of topic-specific words and word order, word correlations and the way words organized into sentence are crucial to intention detection tasks. In this paper, we present a neural network based jointly modeling approach to model and capture user intentions in medical related text queries. Regardless of the exact words in text queries, the proposed method incorporates two types of heterogeneous information: 1) pairwise word feature correlations and 2) part-of-speech tags of a sentence to jointly model user intentions. Variable-length text queries are first inherently taken care of by a fixed-size pairwise feature correlation matrix. Moreover, convolution and pooling operations are applied on feature correlations to fully exploit latent semantic structure within the query. Sentence rephrasing is finally introduced as a data augmentation technique to improve model generalization ability during model training. Experiment results on real world medical queries have shown that the proposed method is able to extract complete and precise user intentions from text queries.

Broad Learning based Multi-Source Collaborative Recommendation

Anchor links connect information entities, such as entities of movies or products, across networks from different sources, and thus information in these networks can be transferred directly via anchor links. Therefore, anchor links have great value to many cross-network applications, such as cross-network social link prediction and cross-network recommendation. In this paper, we focus on studying the recommendation problem that can provide ratings of items or services. To address the problem, we propose a Cross-network Collaborative Matrix Factorization (CCMF) recommendation framework based on broad learning setting, which can effectively integrate multi-source information and alleviate the sparse information problem in each individual network. Based on item anchor links CCMF can fuse item similarity information and item latent information across networks from different sources. And different from most of the traditional works, CCMF can make multi-source recommendation tasks collaborate together via the information transfer based on the broad learning setting. During the transfer process, a novel cross-network similarity transfer method is applied to keep the consistency of item similarities between two different networks, and a domain adaptation matrix is used to overcome the domain difference problem. We conduct experiments to compare the proposed CCMF method with both classic and state-of-the-art recommendation techniques. The experimental results illustrate that CCMF outperforms other methods in different experimental circumstances, and has great advantages on dealing with different data sparse problems.

Extracting Medical Knowledge from Crowdsourced Question Answering Website

The medical crowdsourced question answering (Q&A) websites are booming in recent years, and an increasingly large amount of patients and doctors are involved. The valuable information from these medical crowdsourced Q&A websites can benefit patients, doctors and the society. One key to unleash the power of these Q&A websites is to extract medical knowledge from the noisy question-answer pairs and filter out unrelated or even incorrect information. Facing the daunting scale of information generated on medical Q&A websites everyday, it is unrealistic to fulfill this task via supervised method due to the expensive annotation cost. In this paper, we propose a Medical Knowledge Extraction (MKE) system that can automatically provide high-quality knowledge triples extracted from the noisy question-answer pairs, and at the same time, estimate expertise for the doctors who give answers on these Q&A websites. The MKE system is built upon a truth discovery framework, where we jointly estimate trustworthiness of answers and doctor expertise from the data without any supervision. We further tackle three unique challenges in the medical knowledge extraction task, namely representation of noisy input, multiple linked truths, and the long-tail phenomenon in the data. The MKE system is applied to real-world datasets crawled from xywy.com, one of the most popular medical crowdsourced Q&A websites. Both quantitative evaluation and case studies demonstrate that the proposed MKE system can successfully provide useful medical knowledge and accurate doctor expertise. We further demonstrate a real-world application, Ask A Doctor, which can automatically give patients suggestions to their questions.

CHRS : Cold Start Recommendation Across Multiple Heterogeneous Information Networks

Nowadays, people are overwhelmingly exposed to various kinds of information from different information networks. In order to recommend users with the information entities that match their interests, many recommendation methods have been proposed so far. And some of these methods have explored different ways to utilize different kinds of auxiliary information to deal with the information sparsity problem of user feedbacks. However, as a special kind of information sparsity problem, the “cold start” problem is still a big challenge not well-solved yet in the recommendation problem. In order to tackle the “cold start” challenge, in this paper, we propose a novel recommendation model, which integrates the auxiliary information in multiple heterogeneous information networks (HINs), namely the Cross-HIN Recommendation System (CHRS). By utilizing the rich heterogeneous information from meta-paths, the CHRS is able to calculate the similarities of information entities and apply the calculated similarity scores in the recommendation process. For the information entities shared among multiple information networks, CHRS transfers item latent information from other networks to help the recommendation task in a given network. During the information transfer process, CHRS applies a domain adaptation matrix to tackle the domain difference problem. We conduct experiments to compare our CHRS method with several widely employed or the state-of-art recommendation models, and the experimental results demonstrate that our method outperforms the baseline methods in addressing the “cold start” recommendation problem.

On the Generative Discovery of Structured Medical Knowledge

Online healthcare services can provide the general public with ubiquitous access to medical knowledge and reduce medical information access cost for both individuals and societies. However, expanding the scale of high-quality yet structured medical knowledge usually comes with tedious efforts in data preparation and human annotation. To promote the benefits while minimizing the data requirement in expanding medical knowledge, we introduce a generative perspective to study the relational medical entity pair discovery problem. A generative model named Conditional Relationship Variational Autoencoder is proposed to discover meaningful and novel medical entity pairs by purely learning from the expression diversity in the existing relational medical entity pairs. Unlike discriminative approaches where high-quality contexts and candidate medical entity pairs are carefully prepared to be examined by the model, the proposed model generates novel entity pairs directly by sampling from a learned latent space without further data requirement. The proposed model explores the generative modeling capacity for medical entity pairs while incorporating deep learning for hands-free feature engineering. It is not only able to generate meaningful medical entity pairs that are not yet observed, but also can generate entity pairs for a specific medical relationship. The proposed model adjusts the initial representations of medical entities by addressing their relational commonalities. Quantitative and qualitative evaluations on real-world relational medical entity pairs demonstrate the effectiveness of the proposed method in generating relational medical entity pairs that are meaningful and novel.

Multi-Task Pharmacovigilance Mining from Social Media Posts

Social media has grown to be a crucial information source for pharmacovigilance studies where an increasing number of people post adverse reactions to medical drugs that are previously unreported. Aiming to effectively monitor various aspects of Adverse Drug Reactions (ADRs) from diversely expressed social medical posts, we propose a multi-task neural network framework that learns several tasks associated with ADR monitoring with different levels of supervisions collectively. Besides being able to correctly classify ADR posts and accurately extract ADR mentions from online posts, the proposed framework is also able to further understand reasons for which the drug is being taken, known as »indications», from the given social media post. A coverage-based attention mechanism is adopted in our framework to help the model properly identify »phrasal» ADRs and Indications that are attentive to multiple words in a post. Our framework is applicable in situations where limited parallel data for different pharmacovigilance tasks are available. We evaluate the proposed framework on real-world Twitter datasets, where the proposed model outperforms the state-of-the-art alternatives of each individual task consistently.

Bringing semantic structures to user intent detection in online medical queries

The Internet has revolutionized healthcare by offering medical information ubiquitously to patients via the web search. The healthcare status, complex medical information needs of patients are expressed diversely and implicitly in their medical text queries. Aiming to better capture a focused picture of users medical-related information search and shed insights on their healthcare information access strategies, it is challenging yet rewarding to detect structured user intentions from their diversely expressed medical text queries. We introduce a graph-based formulation to explore structured concept transitions for effective user intent detection in medical queries, where each node represents a medical concept mention and each directed edge indicates a medical concept transition. A deep model based on multi-task learning is introduced to extract structured semantic transitions from user queries, where the model extracts word-level medical concept mentions as well as sentence-level concept transitions collectively. A customized graph-based mutual transfer loss function is designed to impose explicit constraints and further exploit the contribution of mentioning a medical concept word to the implication of a semantic transition. We observe an 8% relative improvement in AUC and 23% relative reduction in coverage error by comparing the proposed model with the best baseline model for the concept transition inference task on real-world medical text queries.

Multi-source Hierarchical Prediction Consolidation

In big data applications such as healthcare data mining, due to privacy concerns, it is necessary to collect predictions from multiple information sources for the same instance, with raw features being discarded or withheld when aggregating multiple predictions. Besides, crowd-sourced labels need to be aggregated to estimate the ground truth of the data. Due to the imperfection caused by predictive models or human crowdsourcing workers, noisy and conflicting information is ubiquitous and inevitable. Although state-of-the-art aggregation methods have been proposed to handle label spaces with flat structures, as the label space is becoming more and more complicated, aggregation under a label hierarchical structure becomes necessary but has been largely ignored. These label hierarchies can be quite informative as they are usually created by domain experts to make sense of highly complex label correlations such as protein functionality interactions or disease relationships. We propose a novel multi-source hierarchical prediction consolidation method to effectively exploits the complicated hierarchical label structures to resolve the noisy and conflicting information that inherently originates from multiple imperfect sources. We formulate the problem as an optimization problem with a closed-form solution. The consolidation result is inferred in a totally unsupervised, iterative fashion. Experimental results on both synthetic and real-world data sets show the effectiveness of the proposed method over existing alternatives.