Multi-scale stacked sequential learning

Sequential learning is the discipline of machine learning that deals with dependent data such that neighboring labels exhibit some kind of relationship. The paper main contribution is two-fold: first, we generalize the stacked sequential learning, highlighting the key role of neighboring interactions modeling. Second, we propose an effective and efficient way of capturing and exploiting sequential correlations that takes into account long-range interactions. We tested the method on two tasks: text lines classification and image pixel classification. Results on these tasks clearly show that our approach outperforms the standard stacked sequential learning as well as state-of-the-art conditional random fields.     

Online error correcting output codes

This article proposes a general extension of the error correcting output codes framework to the online learning scenario. As a result, the final classifier handles the addition of new classes independently of the base classifier used. In particular, this extension supports the use of both online example incremental and batch classifiers as base learners. The extension of the traditional problem independent codings one-versus-all and one-versus-one is introduced. Furthermore, two new codings are proposed, unbalanced online ECOC and a problem dependent online ECOC. This last online coding technique takes advantage of the problem data for minimizing the number of dichotomizers used in the ECOC framework while preserving a high accuracy. These techniques are validated on an online setting of 11 data sets from UCI database and applied to two real machine vision applications: traffic sign recognition and face recognition. As a result, the online ECOC techniques proposed provide a feasible and robust way for handling new classes using any base classifier.     

Mixed Cationic Surfactant Vesicles in (Dioctadecyldimethylammonium Bromide)/NaCl and (Dioctadecyldimethylammonium Chloride)/NaBr Aqueous Dispersions

One of the most challenging characteristics not fully understood yet of the cationic surfactant salt dioctadecyldimethylammonium (DODA⁺) halide is concerned with the effects of the counterion (usually Br⁻ and Cl⁻) on the surfactant assembly into vesicle structures in aqueous solution. These counterions play a key role in the self-organization of DODA⁺ into bilayer structures. Differential scanning calorimetry (DSC) and dynamic light scattering (DLS) techniques were used here to investigate systematically the effects of the single salts NaCl and NaBr, respectively, on the thermal behavior and structural organization of the cationic dioctadecyldimethylammonium bromide and chloride (DODAB and DODAC) in water. The results undoubtedly indicate that the added Br⁻ or Cl⁻, respectively, into DODAC and DODAB aqueous dispersions, replaces partially the bound counterions (Cl⁻ and Br⁻) from the vesicles, yielding formation of DODAB/DODAC mixed vesicles. As a conclusion, single salts may be used to tune the thermal and structural characteristics of cationic vesicles.     

Development and Characterization of a Multiplex Assay to Quantify Complement-Fixing Antibodies against Dengue Virus

Antibodies capable of activating the complement system (CS) when bound with antigen are referred to as “complement-fixing antibodies” and are involved in protection against Flaviviruses. A complement-fixing antibody test has been used in the past to measure the ability of dengue virus (DENV)-specific serum antibodies to activate the CS. As originally developed, the test is time-consuming, cumbersome, and has limited sensitivity for DENV diagnosis. Here, we developed and characterized a novel multiplex anti-DENV complement-fixing assay based on the Luminex platform to quantitate serum antibodies against all four serotypes (DENV1-4) that activate the CS based on their ability to fix the complement component 1q (C1q). The assay demonstrated good reproducibility and showed equivalent performance to a DENV microneutralization assay that has been used to determine DENV serostatus. In non-human primates, antibodies produced in response to primary DENV1-4 infection induced C1q fixation on homologous and heterologous serotypes. Inter-serotype cross-reactivity was associated with homology of the envelope protein. Interestingly, the antibodies produced following vaccination against Zika virus fixed C1q on DENV. The anti-DENV complement fixing antibody assay represents an alternative approach to determine the quality of functional antibodies produced following DENV natural infection or vaccination and a biomarker for dengue serostatus, while providing insights about immunological cross-reactivity among different Flaviviruses.     

Functional analysis of yeast essential genes using a promoter-substitution cassette and the tetracycline-regulatable dual expression system

A promoter-substitution cassette has been constructed that allows one-step substitution of chromosomal gene promoters for the tetracycline-regulatable tetO promoter in yeast cells, which uses kanMX4 as selective marker for geneticin resistance. Oligonucleotides for PCR amplification of the cassette are designed to allow homologous recombination through short flanking regions of homology with the upstream sequences of the chromosomal gene, upon transformation of target cells. By testing three essential genes of chromosome XV (YOL135c, YOL142w and YOL144w), the system causes tetracycline-dependent conditional growth of the cells, being modulatable by intermediate concentrations of the effector. Analysis of terminal phenotypes of the promoter-substituted cells in the presence of the antibiotic may facilitate functional analysis of essential orphan genes. © 1998 John Wiley & Sons, Ltd.     

Antitumor Effects of Ral-GTPases Downregulation in Glioblastoma

Glioblastoma (GBM) is the most common tumor in the central nervous system in adults. This neoplasia shows a high capacity of growth and spreading to the surrounding brain tissue, hindering its complete surgical resection. Therefore, the finding of new antitumor therapies for GBM treatment is a priority. We have previously described that cyclin D1-CDK4 promotes GBM dissemination through the activation of the small GTPases RalA and RalB. In this paper, we show that RalB GTPase is upregulated in primary GBM cells. We found that the downregulation of Ral GTPases, mainly RalB, prevents the proliferation of primary GBM cells and triggers a senescence-like response. Moreover, downregulation of RalA and RalB reduces the viability of GBM cells growing as tumorspheres, suggesting a possible role of these GTPases in the survival of GBM stem cells. By using mouse subcutaneous xenografts, we have corroborated the role of RalB in GBM growth in vivo. Finally, we have observed that the knockdown of RalB also inhibits cell growth in temozolomide-resistant GBM cells. Overall, our work shows that GBM cells are especially sensitive to Ral-GTPase availability. Therefore, we propose that the inactivation of Ral-GTPases may be a reliable therapeutic approach to prevent GBM progression and recurrence.     

A Review of Audio Fingerprinting

An audio fingerprint is a compact content-based signature that summarizes an audio recording. Audio Fingerprinting technologies have attracted attention since they allow the identification of audio independently of its format and without the need of meta-data or watermark embedding. Other uses of fingerprinting include: integrity verification, watermark support and content-based audio retrieval. The different approaches to fingerprinting have been described with different rationales and terminology: Pattern matching, Multimedia (Music) Information Retrieval or Cryptography (Robust Hashing). In this paper, we review different techniques describing its functional blocks as parts of a common, unified framework. Pedro Cano received a B.Sc and M. Sc. Degree in Electrical Engineering from the Universitat Politècnica de Catalunya in 1999. In 1997, he joined the Music Technology Group of the Universitat Pompeu Fabra where he is currently pursuing his Ph.D. on Content-based Audio Identification. He has been assistant professor in the Department of Technologies of the Universitat Pompeu Fabra since 1999. His research interests and recent work include: signal processing for music applications, within a real-time voice morphing system for karaoke applications, pattern matching and information retrieval, specifically content-based audio identification. Eloi Batlle received his M.S. degree in electronic engineering in 1995 from the Politechnical University of Catalunya in Barcelona, Spain. He then joined the Signal Processing Group at the same university where he was working on robust speech recognition. He received a PhD on this subject in 1999. While he was a PhD student he also worked as a researcher at the Telecom Italia Lab during 1997. In 2000 he joined the Audiovisual Institute (a part of the Pompeu Fabra University). Currently he is a member of the Music Technology Group of the same Institute where he leads several reseach projects on music identification and similarity. In 2000 he also joined the Department of Technologies of the Pompeu Fabra University and he teaches several subjects to undergraduate and graduate students. From 2001 he is the Deputy Director of this Department. His research interests include information theory, music similary, statistical signal processing and pattern recognition. Ton Kalker was born in The Netherlands in 1956. He received his M.S. degree in mathematics in 1979 from the University of Leiden, The Netherlands. From 1979 until 1983, while he was a Ph.D. candidate, he worked as a Research Assistant at the University of Leiden. From 1983 until December 1985 he worked as a lecturer at the Computer Science Department of the Technical University of Delft. In January 1986 he received his Ph.D. degree in Mathematics. In December 1985 he joined the Philips Research Laboratories Eindhoven. Until January 1990 he worked in the field of Computer Aided Design. He specialized in (semi) automatic tools for system verification. Currently he is a member of the Processing and Architectures for Content MANagement group (PACMAN) of Philips Research, where he is working on security of multimedia content, with an emphasis on watermarking and fingerprinting for video and audio. In November 1999 he became a part-time professor in the Signal Processing Systems group of Jan Bergmans in the area of ‘signal processing methods for data protection’. He is a Fellow of the IEEE for his contributions to practical applications of watermarking, in particular watermarking for DVD-Video copy protection. His other research interests include wavelets, multirate signal processing, motion estimation, psycho physics, digital video compression and medical image processing. Jaap Haitsma was born in 1974 in Easterein, the Netherlands. He received his B.Sc. in Electronic Engineering from the Noordelijke Hogeschool Leeuwarden in 1997. He did his thesis in 1997 at the Philips Research Laboratories in Redhill, England, on the topic of: “Colour Management for Liquid Crystal Displays”. Currently he is with the Philips Research Laboratories, Eindhoven, the Netherlands, where he has been doing research into digital watermarking and fingerprinting of audio and video since late 1997. From 1999 to 2002 he was also a part-time student at the Technical University of Eindhoven, where he obtained his M.Sc. in Electronic Engineering. His areas of interest include digital signal processing, database search algorithms and software engineering.