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Exploring Disease Interactions Using Markov Networks
Haaren, Jan Van (Katholieke Universiteit Leuven) | Davis, Jesse (Katholieke Universiteit Leuven) | Lappenschaar, Martijn (Radboud Universiteit Nijmegen) | Hommersom, Arjen (Radboud Universiteit Nijmegen)
Network medicine is an emerging paradigm for studying the co-occurrence between diseases. While diseases are often interlinked through complex patterns, most of the existing work in this area has focused on studying pairwise relationships between diseases. In this paper, we use a state-of-the-art Markov network learning method to learn interactions between musculoskeletal disorders and cardiovascular diseases and compare this to pairwise approaches. Our experimental results confirm that the sophisticated structure learner produces more accurate models, which can help reveal interesting patterns in the co-occurrence of diseases.
Exploring Disease Interactions Using Markov Networks
Haaren, Jan Van (Katholieke Universiteit Leuven) | Davis, Jesse (Katholieke Universiteit Leuven) | Lappenschaar, Martijn (Radboud Universiteit Nijmegen) | Hommersom, Arjen (Radboud Universiteit Nijmegen)
Network medicine is an emerging paradigm for studying the co-occurrence between diseases. While diseases are often interlinked through complex patterns, most of the existing work in this area has focused on studying pairwise relationships between diseases. In this paper, we use a state-of-the-art Markov network learning method to learn interactions between musculoskeletal disorders and cardiovascular diseases and compare this to pairwise approaches. Our experimental results confirm that the sophisticated structure learner produces more accurate models, which can help reveal interesting patterns in the co-occurrence of diseases.
Conditional Outlier Approach for Detection of Unusual Patient Care Actions
Hauskrecht, Milos (University of Pittsburgh) | Visweswaran, Shyam (University of Pittsburgh) | Cooper, Gregory (University of Pittsburgh) | Clermont, Gilles (University of Pittsburgh)
Developing methods that can identify important patterns in complex large-scale temporal datasets is one of the key challenges in machine learning and data mining research. Our work focuses on the development of methods that can, based on past data, identify unusual patient-management actions in the Electronic Medical Record (EMR) of the current patient and raise alerts if such actions are encountered. We developed and evaluated a conditional-outlier detection approach for identifying clinical actions such as omissions of medication orders or laboratory orders in the intensive care unit (ICU) that are unusual with respect to past patient care. We used data from 24,658 ICU patient admissions to first learn the outlier models and then to generate 240 medication and laboratory omission alerts. The alerts were evaluated by a group of 18 intensive care physicians. The results show the true positive alert rate for all study alerts ranged from 0.42 to 0.53, which is promising and compares favorably to the positive alert rates of existing clinical alerting systems.
Electricity Demand Forecasting using Gaussian Processes
Blum, Manuel (University of Freiburg) | Riedmiller, Martin (University of Freiburg)
We present an electricity demand forecasting algorithm based on Gaussian processes. By introducing a task-specific, custom covariance function k_power, which incorporates all available seasonal information as well as weather data, we are able to make accurate predictions of power consumption and renewable energy production. The hyper-parameters of the Gaussian process are optimized automatically using marginal likelihood maximization. There are no parameters to be specified by the user. We evaluate the prediction performance on simulated data and get superior results compared to a simple baseline method.
A Comparison of Playlist Generation Strategies for Music Recommendation and a New Baseline Scheme
Bonnin, Geoffray (Technische Universitรคt Dortmund) | Jannach, Dietmar (Technische Universitรคt Dortmund)
The digitalization of music and the instant availability of millions of tracks on the Internet require new approaches to support the user in the exploration of these huge music collections. One possible approach to address this problem, which can also be found on popular online music platforms, is the use of user-created or automatically generated playlists (mixes). The automated generation of such playlists represents a particular type of the music recommendation problem with two special characteristics. First, the tracks of the list are usually consumed immediately at recommendation time; secondly, songs are listened to mostly in consecutive order so that the sequence of the recommended tracks can be relevant. In the past years, a number of different approaches for playlist generation have been proposed in the literature. In this paper, we review the existing core approaches to playlist generation, discuss aspects of appropriate offline evaluation designs and report the results of a comparative evaluation based on different datasets. Based on the insights from these experiments, we propose a comparably simple and computationally tractable new baseline algorithm for future comparisons, which is based on track popularity and artist information and is competitive with more sophisticated techniques in our evaluation settings.
A Preliminary Investigation into Predictive Models for Adverse Drug Events
Davis, Jesse (Katholieke Universiteit Leuven) | Costa, Vitor Santos (Universidade do Porto) | Peissig, Peggy (Marshfield Clinic) | Caldwell, Michael (Marshfield Clinic) | Page, David (University of Wisconsin - Madison)
Adverse drug events are a leading cause of danger and cost in health care. We could reduce both the danger and the cost if we had accurate models to predict, at prescription time for each drug, which patients are most at risk for known adverse reactions to that drug, such as myocardial infarction (MI, or "heart attack") if given a Cox2 inhibitor, angioedema if given an ACE inhibitor, or bleeding if given an anticoagulant such as Warfarin. We address this task for the specific case of Cox2 inhibitors, a type of non-steroidal anti-inflammatory drug (NSAID) or pain reliever that is easier on the gastrointestinal system than most NSAIDS. Because of the MI adverse drug reaction, some but not all very effective Cox2 inhibitors were removed from the market. Specifically, we use machine learning to predict which patients on a Cox2 inhibitor would suffer an MI. An important issue for machine learning is that we do not know which of these patients might have suffered an MI even without the drug. To begin to make some headway on this important problem, we compare our predictive model for MI for patients on Cox2 inhibitors against a more general model for predicting MI among a broader population not on Cox2 inhibitors.
The Baseline Approach to Agent Evaluation
Davidson, Josh (University of Alberta) | Archibald, Christopher (University of Alberta) | Bowling, Michael (University of Alberta)
An important aspect of agent evaluation in stochastic games, especially poker, is the need to reduce the outcome variance in order to get accurate and significant results. The current method used in the Annual Computer Poker Competitionโs analysis is that of duplicate poker, an approach that leverages the ability to deal sets of cards to agents in order to reduce variance. This work explores a different approach to variance reduction by using a control variate based approach known as baseline. The baseline approach involves using an agentโs outcome in self play to create an unbiased estimator for use in agent evaluation and has been shown to work well in both poker and trading agent competition domains. Base- line does not require that the agents are able to be dealt sets of cards, making it a more robust technique than duplicate. This approach is compared to the current duplicate method, as well as other variations of duplicate poker on the results of the 2011 two player no-limit and three player limit Texas Holdโem ACPC tournaments.
An Evolutionary Search Algorithm to Guide Stochastic Search for Near-Native Protein Conformations with Multiobjective Analysis
Olson, Brian (George Mason University) | Shehu, Amarda (George Mason University)
Predicting native conformations of a protein sequence is known as de novo structure prediction and is a central challenge in computational biology. Most computational protocols employ Monte Carlo sampling. Evolutionary search algorithms have also been proposed to enhance sampling of near-native conformations. These approaches bias stochastic search by an energy function, even though current energy functions are known to be inaccurate and drive sampling to non-native energy minima. This paper proposes a multiobjective approach which employs Pareto dominance, rather than total energy, to evaluate a conformation. This multiobjective approach accounts for the fact that terms in an energy function are conflicting optimization criteria. Our analysis is conducted on a diverse set of 20 proteins. Results show that employing Pareto dominance, rather than total energy, to guide stochastic search is more effective at sampling conformations which are both lower in energy and near the protein native structure.
Solving Security Games on Graphs via Marginal Probabilities
Letchford, Joshua (Duke University) | Conitzer, Vincent (Duke University)
Security games involving the allocation of multiple security resources to defend multiple targets generally have an exponential number of pure strategies for the defender. One method that has been successful in addressing this computational issue is to instead directly compute the marginal probabilities with which the individual resources are assigned (first pursued by Kiekintveld et al. (2009)). However, in sufficiently general settings, there exist games where these marginal solutions are not implementable, that is, they do not correspond to any mixed strategy of the defender. In this paper, we examine security games where the defender tries to monitor the vertices of a graph, and we show how the type of graph, the type of schedules, and the type of defender resources affect the applicability of this approach. In some settings, we show the approach is applicable and give a polynomial-time algorithm for computing an optimal defender strategy; in other settings, we give counterexample games that demonstrate that the approach does not work, and prove NP-hardness results for computing an optimal defender strategy.