Research Publications
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By Type By Year By Research Group | The introduction of plug-in electric vehicles (PEVs) represents an unprecedented interaction between the road network and electricity grid. By replacing the traditional fuel source, petrol, with electricity, PEVs will increase the demand for electric ... Measuring cognitive load changes can contribute to better treatment of patients, can help design effective strategies to reduce medical errors among clinicians and can facilitate user evaluation of health care information systems. This paper proposes an ... High cognitive load arises from complex time- and safety-critical tasks (e.g., mapping out flight paths, monitoring traffic, or even managing nuclear reactors), which cause stress, errors and diminished performance. Over the past five years, our research ... The recently proposed ImageNet dataset consists of several million images, each annotated with a single object category. These annotations may be imperfect, in the sense that many images contain multiple objects belonging to the label vocabulary. In ... We propose an efficient algorithm for calculating hold-out and cross-validation (CV) type of estimates for sparse regularized least-squares predictors. Holding out H data points with our method requires O(min(nH^2,Hn^2)) time provided that a predictor ... In this article we review the 2011 International Planning Competition. We give an overview of the history of the competition, discussing how it has developed since its first edition in 1998. The 2011 competition was run in three main separate tracks: ... Online forums are rich sources of information about users' communication activity over time. Finding temporal patterns in communication records can advance our understanding of the dynamics of conversations. The main challenge of temporal analysis in ... Mixability of a loss governs the best possible performance when aggregating expert predictions with respect to that loss. The determination of the mixability constant for binary losses is straightforward but opaque. In the binary case we make this ... The problem of isometric point-pattern matching can be modeled as inference in small tree-width graphical models whose embeddings in the plane are said to be ‘globally rigid’. Although such graphical models lead to efficient and exact solutions, they ... Background: This work describes a system for identifying event mentions in bio-molecular research abstracts that are either speculative (e.g. analysis of IkappaBalpha phosphorylation, where it is not specified whether phosphorylation did or did not occur... Compressive sensing is an emerging field predicated upon the fact that, if a signal has a sparse representation in some basis, then it can be almost exactly reconstructed from very few random measurements. Many signals and natural images, for example ... The two parameter Poisson-Dirichlet Process (PDP), a generalisation of the Dirichlet Process, is increasingly being used for probabilistic modelling in discrete areas such as language technology, bioinformatics, and image analysis. There is a rich ... Environmental issues have become more salient in the global political and social consciousness, leading to Human-Computer Interaction research exploring solutions to environment imbalances and climate change. We study losses for binary classifi cation and class probability estimation and extend the understanding of them from margin losses to general composite losses which are the composition of a proper loss with a link function. We characterise when margin... Let (S, d) be a finite metric space, where each element p 2 S has a non-negative weight wt(p). We study t-spanners for the set S with respect to the following weighted distance function d!: d!(p, q) = 0 if p = q, wt(p) + d(p, q) + wt(q) if p 6= q.... Abstract Cell tracking is a key task in the high-throughput quantitative study of important biological processes, such as immune system regulation and neurogenesis. Variability in cell density and dynamics in different videos, hampers portability of ... Algorithms for determining quality/cost/price tradeo ffs in saturated markets are considered. A product is modeled by d real-valued qualities whose sum determines the unit cost of producing the product. This leads to the following optimization problem: ... We are given a trajectory $\T$ and an area $\A$. $\T$ might intersect $\A$ several times, and our aim is to detect whether $\T$ visits $\A$ with some regularity, e.g.~what is the longest time span that a GPS-GSM equipped elephant visited a specific lake... Background Free text is helpful for entering information into electronic health records, but reusing it is a challenge. The need for language technology for processing Finnish and Swedish healthcare text is therefore evident; however Finnish and ... Medical Subject Headings (MeSH) are used to index the majority of databases generated by the National Library of Medicine. Essentially, MeSH terms are designed to make information, such as scientific articles, more retrievable and assessable to users of... A graph $G$ is an $\alpha$ angle crossing ($\alpha$AC) graph if every pair of crossing edges in $G$ intersect at an angle of at least $\alpha$. The concept of right angle crossing (RAC) graphs ($\alpha=\pi/2$) was recently introduced by Didimo \etal\ ... Maximum A Posteriori inference in graphical models is often solved via message-passing algorithms, such as the junction-tree algorithm or loopy belief-propagation. The exact solution to this problem is well-known to be exponential in the size of the ... This paper investigates Factored Markov Decision Processes with Imprecise Probabilities (MDPIPs); that is, Factored Markov Decision Processes (MDPs) where transition probabilities are imprecisely specified. We derive efficient approximate solutions for... Speech is a promising modality for the convenient measurement of cognitive load, and recent years have seen the development of several cognitive load classification systems. Many of these systems have utilised mel Frequency Cepstral Coefficients (MFCC) ... AIM: Given a set of pre-defined medical categories used in Evidence Based Medicine, we aim to automatically annotate sentences in medical abstracts with these labels. METHOD: We constructed a corpus of 1,000 medical abstracts annotated by hand with ... This paper describes a method for detecting event trigger words in biomedical text based on a word sense disambiguation (WSD) approach. We first investigate the applicability of existing WSD techniques to trigger word disambiguation in the BioNLP 2009 ... We unify f-divergences, Bregman divergences, surrogate regret bounds, proper scoring rules, cost curves, ROC-curves and statistical information. We do this by systematically studying integral and variational representations of these objects and in so ... Cognitive load measurement systems measure the mental demand experienced by human while performing a cognitive task, which is useful in monitoring and enhancing task performance. Various speech-based systems have been proposed for cognitive load ... When modeling real-world decision-theoretic planning problems in the Markov Decision Process (MDP) framework, it is often impossible to obtain a completely accurate estimate of transition probabilities. For example, natural uncertainty arises in the ... This paper introduces a principled approach for the design of a scalable general reinforcement learning agent. Our approach is based on a direct approximation of AIXI, a Bayesian optimality notion for general reinforcement learning agents. Previously, it ... The performance of speaker verification systems degrades considerably when the test segments are utterances of very short duration. This might be either due to variations in score-matching arising from the unobserved speech sounds of short speech ... Developing a fusion-based system is one of the key research issues in modern Language Identification (LID) systems. In this paper we investigate existing fusion techniques for LID systems and propose an alternative solution.By directly utilizing ... The use of simultaneous masking in speech enhancement has shown promise for a range of noise types. In this paper, a new speech enhancement algorithm based on a short-term temporal masking threshold to noise ratio (MNR) is presented. A novel functional ... Widespread availability of location aware devices (such as GPS receivers) promotes capture of detailed movement trajectories of people, animals, vehicles and other moving objects. We investigate spatio-temporal movement patterns in large tracking data ... In this paper we discuss the complexity and approximability of the minimum corridor connection problem where, given a rectilinear decomposition of a rectilinear polygon into ``rooms'', one has to find the minimum length tree along the edges of the ... A trajectory is a sequence of locations, each associated with a timestamp, describing the movement of a point. Trajectory data is becoming increasingly available and the size of recorded trajectories is getting larger. In this paper we study the problem ... Consider the following problem: given sets of unlabeled observations, each set with known label proportions, predict the labels of another set of observations, possibly with known label propor- tions. This problem occurs in areas like e-commerce, ... We propose hashing to facilitate efficient kernels. This generalizes previous work using sampling and we show a principled way to compute the kernel matrix for data streams and sparse feature spaces. Moreover, we give deviation bounds from the exact ... As a fundamental problem in pattern recognition, graph matching has applications in a variety of fields, from computer vision to computational biology. In graph matching, patterns are modeled as graphs and pattern recognition amounts to finding a ... It has been shown that isometric matching problems can be solved exactly in polynomial time, by means of a Junction Tree with small maximal clique size. Recently, an iterative algorithm was presented which converges to the same solution an order of ... Recently, subband frame-averaged frequency modulation (FM) as a complementary feature to amplitude-based features for several speech based classification problems including speaker recognition has shown promise. One problem with using FM extraction in ... Widespread availability of location aware devices (such as GPS receivers) promotes capture of detailed movement trajectories of people, animals, vehicles and other moving objects, opening new options for a better understanding of the processes involved.... A recent paper [1] proposed a provably optimal polynomial time method for performing near-isometric point pattern matching by means of exact probabilistic inference in a chordal graphical model. Its fundamental result is that the chordal graph in ... The aperture angle a(x,Q) of a point x in Q in the plane with respect to a convex polygon Q is the angle of the smallest cone with apex x that contains Q. The aperture angle approximation error of a compact convex set C in the plane with respect to an ... Given a set S of n points in R^D, and an integer k such that 0 < k < n, we show that a geometric graph with vertex set S, at most n − 1 + k edges, maximum degree five, and dilation O(n/(k + 1)) can be computed in time O(n log n). For any k, we also ... Given a set S of n points in d dimensional Euclidean space, and an integer k such that 0 <= k < n, we show that a geometric graph with vertex set S, at most n − 1 + k edges, maximum degree five, and dilation O(n/(k + 1)) can be computed in time O(n log n)... A wireless ad-hoc network can be represented as a graph in which the nodes represent wireless devices, and the links represent pairs of nodes that communicate directly by means of radio signals. The interference caused by a link between two nodes u and v... When human raters are presented with a collection of shapes and asked to rank them according to their aesthetic appeal, the results often indicate that there is a statistical consensus among the raters. Yet it might be difficult to define a succinct ... Given a Euclidean graph G in R^d with n vertices and m edges, we consider the problem of adding an edge to G such that the stretch factor of the resulting graph is minimized. Currently, the fastest algorithm for computing the stretch factor of a graph ... Given an arbitrary real constant \eps > 0, and a geometric graph G in d-dimensional Euclidean space with n points, O(n) edges, and constant dilation, our main result is a data structure that answers (1+\eps)-approximate shortest path length queries in ... Data representing moving objects is rapidly getting more available, especially in the area of wildlife GPS tracking. It is a central belief that information is hidden in large data sets in the form of interesting patterns, where a pattern can be any ... We consider the problem of computing a minimum weight pseudo-triangulation of a set S of n points in the plane. We first present an O(n log n)-time algorithm that produces a pseudo-triangulation of weight O(log n * wt(M(S))) which is shown to be ... The "rich-club phenomenon" in complex networks is characterized when nodes of higher degree are more interconnected than nodes with lower degree. The presence of this phenomenon may indicate several interesting high-level network properties, such as ... Let H1 = (V,E1) be a collection of N pairwise vertex disjoint O(1)-spanners where the weight of an edge is equal to the Euclidean distance between its endpoints. Let H2 = (V,E2) be the graph on V with M edges of non-negative weight. The union of the two ... Moving point object data can be analyzed through the discovery of patterns. We consider the computational e±ciency of detecting four such spatio-temporal patterns, namely flock, leadership, convergence, and encounter, as defined by Laube et al., 2004. ... Given a polygonal path P with vertices p1, , pn in R^d and a real number t>1, a path Q = (pi1, pi2, , pik) is a t-distance preserving approximation of P if 1 = i1 < i2 < < ik = n and each straight-line edge (pij ; pij+1) of Q approximates the ... Objective: Analyses of novel linguistic and grammatical features, extracted from transcribed speech of people working in collaborative environment, for cognitive load measurement. Background: Prior studies have attempted to assess users’ cognitive load ... In this paper, we propose a biologically inspired framework of visual tracking based on proto-objects. Given an image sequence, proto-objects are first detected by combining saliency map and topic model. Then the target is tracked based on spatial and ... We experience cognitive load, i.e. in the executive control of working memory, during critical tasks and other activities such as learning. While engaged in these activities our affective states i.e. emotions, can be induced by the task itself or by ... |