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UCL University College London Eprints (386,324 recursos)

UCL Eprints collects the work of UCL researchers and makes it freely available over the web, helping the worldwide scholarly community to discover UCL research. Institutional repositories like UCL Eprints complement the traditional academic publishing and scholarly communications processes. They raise the visibility of research and help to maximise its impact. UCL researchers are encouraged to deposit a copy of each journal article, conference paper, working paper, and any other research output, in the UCL Eprints at the earliest opportunity, ensuring that their research reaches as wide an audience as possible.

Mostrando recursos 61 - 80 de 389,364

  1. Efficient Orthogonal Tensor Decomposition, with an Application to Latent Variable Model Learning

    Király, FJ
    Decomposing tensors into orthogonal factors is a well-known task in statistics, machine learning, and signal processing. We study orthogonal outer product decompositions where the factors in the summands in the decomposition are required to be orthogonal across summands, by relating this orthogonal decomposition to the singular value decompositions of the flattenings. We show that it is a non-trivial assumption for a tensor to have such an orthogonal decomposition, and we show that it is unique (up to natural symmetries) in case it exists, in which case we also demonstrate how it can be efficiently and reliably obtained by a sequence...

  2. Error-minimizing estimates and universal entry-wise error bounds for low-rank matrix completion

    Király, FJ; Theran, L
    We propose a general framework for reconstructing and denoising single entries of incomplete and noisy entries. We describe: effective algorithms for deciding if and entry can be reconstructed and, if so, for reconstructing and denoising it; and a priori bounds on the error of each entry, individually. In the noiseless case our algorithm is exact. For rank-one matrices, the new algorithm is fast, admits a highly-parallel implementation, and produces an error minimizing estimate that is qualitatively close to our theoretical and the state-of-the-art Nuclear Norm and OptSpace methods.

  3. Kernels for sequentially ordered data

    Király, FJ; Oberhauser, H
    We present a novel framework for kernel learning with sequential data of any kind, such as time series, sequences of graphs, or strings. Our approach is based on signature features which can be seen as an ordered variant of sample (cross-)moments; it allows to obtain a "sequentialized" version of any static kernel. The sequential kernels are efficiently computable for discrete sequences and are shown to approximate a continuous moment form in a sampling sense. A number of known kernels for sequences arise as "sequentializations" of suitable static kernels: string kernels may be obtained as a special case, and alignment kernels...

  4. Physical determinants of the self-replication of protein fibrils

    Šaric, A; Buell, AK; Meisl, G; Michaels, TCT; Dobson, CM; Linse, S; Knowles, TPJ; Frenkel, D
    © 2006 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.The ability of biological molecules to replicate themselves is the foundation of life, requiring a complex cellular machinery. However, a range of aberrant processes involve the self-replication of pathological protein structures without any additional assistance. One example is the autocatalytic generation of pathological protein aggregates, including amyloid fibrils, involved in neurodegenerative disorders. Here, we use computer simulations to identify the necessary requirements for the self-replication of fibrillar assemblies of proteins. We establish that a key physical determinant for this process is the affinity of proteins for the surfaces of...

  5. Crucial role of nonspecific interactions in amyloid nucleation.

    Šarić, A; Chebaro, YC; Knowles, TP; Frenkel, D
    Protein oligomers have been implicated as toxic agents in a wide range of amyloid-related diseases. However, it has remained unsolved whether the oligomers are a necessary step in the formation of amyloid fibrils or just a dangerous byproduct. Analogously, it has not been resolved if the amyloid nucleation process is a classical one-step nucleation process or a two-step process involving prenucleation clusters. We use coarse-grained computer simulations to study the effect of nonspecific attractions between peptides on the primary nucleation process underlying amyloid fibrillization. We find that, for peptides that do not attract, the classical one-step nucleation mechanism is possible...

  6. Corrigendum to 'Obtaining T1-T2 distribution functions from 1-dimensional T1 and T2 measurements: The pseudo 2-D relaxation model' [J. Magn. Reson. 269 (2016) 186-195].

    Williamson, NH; Röding, M; Galvosas, P; Miklavcic, SJ; Nydén, M

  7. Language-dependent changes in pitch-relevant neural activity in the auditory cortex reflect differential weighting of temporal attributes of pitch contours

    Krishnan, A; Gandour, JT; Xu, Y; Suresh, CH

  8. Consuming cultures

    Brah, A; Coombes, AE; Lewis, R; Phoenix, A

  9. Snakes and ladders: Reviewing feminisms at century's end

    Hall, C; O'Sullivan, S; Phoenix, A; Storr, M; Thomas, L; Whitehead, A

  10. 'They give you tools and they give you a lot, but it is up to you to use them': the creation of performing artists through an integrated learning and teaching curriculum

    Guile, D; Okumoto, K

  11. Coding Second Language Data Validly and Reliably

    Révész, A

  12. Text characteristics of task input and difficulty in second language listening comprehension

    Révész, A; Brunfaut, T
    This study investigated the effects of a group of task factors on advanced English as a second language learners' actual and perceived listening performance. We examined whether the speed, linguistic complexity, and explicitness of the listening text along with characteristics of the text necessary for task completion influenced comprehension. We also explored learners' perceptions of what textual factors cause difficulty. The 68 participants performed 18 versions of a listening task, and each task was followed by a perception questionnaire. Nine additional students engaged in stimulated recall. The listening texts were analyzed in terms of a variety of measures, utilizing automatized...

  13. The effects of complexity, accuracy, and fluency on communicative adequacy in oral task performance

    Révész, A; Ekiert, M; Torgersen, E
    Communicative adequacy is a key construct in second language research, as the primary goal of most language learners is to communicate successfully in real-world situations. Nevertheless, little is known about what linguistic features contribute to communicatively adequate speech. This study fills this gap by investigating the extent to which complexity, accuracy, and fluency (CAF) predict adequacy, and whether proficiency and task type moderate these relationships. In all, 20 native speakers and 80 second language users from four proficiency levels performed five tasks. Speech samples were rated for adequacy and coded for a range of CAF indices. Filled pause frequency, a...

  14. Research methods in task-based language teaching

    Révész, A

  15. Task-induced content-familiarity, task-driven attention to form, and learner uptake of recasts: A preliminary inquiry

    Révész, A

  16. Task content familiarity, task type, and efficacy of recasts

    Révész, A; Han, Z-H
    The role of recasts has been the subject of an increasing number of second language acquisition (SLA) studies in recent years, as has been the role of tasks. Few studies, nevertheless, exist that investigate the interaction between the two. The present study makes a preliminary excursion into this unexplored domain by examining the impact of two task variables, task content familiarity and task type, on the efficacy of recasts. A total of 36 adult ESL learners participated in the study, and were randomly assigned to one of the four experimental groups: the Same Video group, the Different Video Group, the...

  17. English in Europe today. Sociocultural and educational perspectives

    Revesz, A

  18. Understanding Second Language Process

    Han, Z-H; Park, E-S; Révész, A; Combs, C; Kim, J-H
    Assembles 11 analytical and empirical studies on the process of second language acquisition, probing an array of issues, from transfer appropriate processing to L2 default processing strategies, among hearing or deaf learners of a variety ...

  19. The ultimate error buster

    Dóczi, B; Prievara, T; Révész, A

  20. How to avoid the comparative fallacy during data analysis: A review of Doughty and Varela (1998) and Mackey (1999).

    Révész, A

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