Página 8 dos resultados de 9995 itens digitais encontrados em 0.315 segundos

‣ Electric field enhanced hydrogen storage on polarizable materials substrates

Zhou, J.; Wang, Q.; Sun, Q.; Jena, P.; Chen, X. S.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Using density functional theory, we show that an applied electric field can substantially improve the hydrogen storage properties of polarizable substrates. This new concept is demonstrated by adsorbing a layer of hydrogen molecules on a number of nanomaterials. When one layer of H2 molecules is adsorbed on a BN sheet, the binding energy per H2 molecule increases from 0.03 eV/H2 in the field-free case to 0.14 eV/H2 in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt% is consistent with the 6 wt% system target set by Department of Energy for 2010. The strength of the electric field can be reduced if the substrate is more polarizable. For example, a hydrogen adsorption energy of 0.14 eV/H2 can be achieved by applying an electric field of 0.03 a.u. on an AlN substrate, 0.006 a.u. on a silsesquioxane molecule, and 0.007 a.u. on a silsesquioxane sheet. Thus, application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H2 molecules can be easily released, thus making storage reversible with fast kinetics. In addition, we show that materials with rich low-coordinated nonmetal anions are highly polarizable and can serve as a guide in the design of new hydrogen storage materials.

‣ Imaging and manipulation of the competing electronic phases near the Mott metal-insulator transition

Kim, Tae-Hwan; Angst, M.; Hu, B.; Jin, R.; Zhang, X.-G.; Wendelken, J. F.; Plummer, E. W.; Li, An-Ping
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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The complex interplay between the electron and lattice degrees of freedom produces multiple nearly degenerate electronic states in correlated electron materials. The competition between these degenerate electronic states largely determines the functionalities of the system, but the invoked mechanism remains in debate. By imaging phase domains with electron microscopy and interrogating individual domains in situ via electron transport spectroscopy in double-layered Sr3(Ru1-xMnx)2O7 (x = 0 and 0.2), we show in real-space that the microscopic phase competition and the Mott-type metal-insulator transition are extremely sensitive to applied mechanical stress. The revealed dynamic phase evolution with applied stress provides the first direct evidence for the important role of strain effect in both phase separation and Mott metal-insulator transition due to strong electron-lattice coupling in correlated systems.

‣ Genome-wide identification of cis-regulatory motifs and modules underlying gene coregulation using statistics and phylogeny

Rouault, Hervé; Mazouni, Khalil; Couturier, Lydie; Hakim, Vincent; Schweisguth, François
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Cell fate determination depends in part on the establishment of specific transcriptional programs of gene expression. These programs result from the interpretation of the genomic cis-regulatory information by sequence-specific factors. Decoding this information in sequenced genomes is an important issue. Here, we developed statistical analysis tools to computationally identify the cis-regulatory elements that control gene expression in a set of coregulated genes. Starting with a small number of validated and/or predicted cis-regulatory modules (CRMs) in a reference species as a training set, but with no a priori knowledge of the factors acting in trans, we computationally predicted transcription factor binding sites (TFBSs) and genomic CRMs underlying coregulation. This method was applied to the gene expression program active in Drosophila melanogaster sensory organ precursor cells (SOPs), a specific type of neural progenitor cells. Mutational analysis showed that four, including one newly characterized, out of the five top-ranked families of predicted TFBSs were required for SOP-specific gene expression. Additionaly, 19 out of the 29 top-ranked predicted CRMs directed gene expression in neural progenitor cells, i.e., SOPs or larval brain neuroblasts...

‣ Discovery of drug mode of action and drug repositioning from transcriptional responses

Iorio, Francesco; Bosotti, Roberta; Scacheri, Emanuela; Belcastro, Vincenzo; Mithbaokar, Pratibha; Ferriero, Rosa; Murino, Loredana; Tagliaferri, Roberto; Brunetti-Pierri, Nicola; Isacchi, Antonella; di Bernardo, Diego
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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A bottleneck in drug discovery is the identification of the molecular targets of a compound (mode of action, MoA) and of its off-target effects. Previous approaches to elucidate drug MoA include analysis of chemical structures, transcriptional responses following treatment, and text mining. Methods based on transcriptional responses require the least amount of information and can be quickly applied to new compounds. Available methods are inefficient and are not able to support network pharmacology. We developed an automatic and robust approach that exploits similarity in gene expression profiles following drug treatment, across multiple cell lines and dosages, to predict similarities in drug effect and MoA. We constructed a “drug network” of 1,302 nodes (drugs) and 41,047 edges (indicating similarities between pair of drugs). We applied network theory, partitioning drugs into groups of densely interconnected nodes (i.e., communities). These communities are significantly enriched for compounds with similar MoA, or acting on the same pathway, and can be used to identify the compound-targeted biological pathways. New compounds can be integrated into the network to predict their therapeutic and off-target effects. Using this network...

‣ A genetic mosaic approach for neural circuit mapping in Drosophila

Bohm, Rudolf A.; Welch, William P.; Goodnight, Lindsey K.; Cox, Logan W.; Henry, Leah G.; Gunter, Tyler C.; Bao, Hong; Zhang, Bing
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Transgenic manipulation of subsets of brain cells is increasingly used for studying behaviors and their underlying neural circuits. In Drosophila, the GAL4–upstream activating sequence (UAS) binary system is powerful for gene manipulation, but GAL4 expression is often too broad for fine mapping of neural circuits. Here, we describe the development of unique molecular genetic tools to restrict GAL4 expression patterns. Building on the GAL4-UAS system, our method adds two components: a collection of enhancer-trap recombinase, Flippase (ET-FLP), transgenic lines that provide inheritable, reproducible, and tissue-specific FLP and an FRT-dependent GAL80 “flip-in” construct that converts FLP expression into tissue-specific repression of GAL4 by GAL80. By including a UAS-encoded fluorescent protein, circuit morphology can be simultaneously marked while the circuit function is assessed using another UAS transgene. In a proof-of-principle analysis, we applied this ET-FLP-induced intersectional GAL80/GAL4 repression (FINGR) method to map the neural circuitry underlying fly wing inflation. The FINGR system is versatile and powerful in combination with the vast collection of GAL4 lines for neural circuit mapping as well as for clonal analysis based on the infusion of the yeast-derived FRT/FLP system of mitotic recombination into Drosophila. The strategies and tactics underlying our FINGR system are also applicable to other genetically amenable organisms in which transgenes including the GAL4...

‣ A binary search approach to whole-genome data analysis

Brodsky, Leonid; Kogan, Simon; BenJacob, Eshel; Nevo, Eviatar
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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A sequence analysis-oriented binary search-like algorithm was transformed to a sensitive and accurate analysis tool for processing whole-genome data. The advantage of the algorithm over previous methods is its ability to detect the margins of both short and long genome fragments, enriched by up-regulated signals, at equal accuracy. The score of an enriched genome fragment reflects the difference between the actual concentration of up-regulated signals in the fragment and the chromosome signal baseline. The “divide-and-conquer”-type algorithm detects a series of nonintersecting fragments of various lengths with locally optimal scores. The procedure is applied to detected fragments in a nested manner by recalculating the lower-than-baseline signals in the chromosome. The algorithm was applied to simulated whole-genome data, and its sensitivity/specificity were compared with those of several alternative algorithms. The algorithm was also tested with four biological tiling array datasets comprising Arabidopsis (i) expression and (ii) histone 3 lysine 27 trimethylation CHIP-on-chip datasets; Saccharomyces cerevisiae (iii) spliced intron data and (iv) chromatin remodeling factor binding sites. The analyses’ results demonstrate the power of the algorithm in identifying both the short up-regulated fragments (such as exons and transcription factor binding sites) and the long—even moderately up-regulated zones—at their precise genome margins. The algorithm generates an accurate whole-genome landscape that could be used for cross-comparison of signals across the same genome in evolutionary and general genomic studies.

‣ Experimental library screening demonstrates the successful application of computational protein design to large structural ensembles

Allen, Benjamin D.; Nisthal, Alex; Mayo, Stephen L.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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The stability, activity, and solubility of a protein sequence are determined by a delicate balance of molecular interactions in a variety of conformational states. Even so, most computational protein design methods model sequences in the context of a single native conformation. Simulations that model the native state as an ensemble have been mostly neglected due to the lack of sufficiently powerful optimization algorithms for multistate design. Here, we have applied our multistate design algorithm to study the potential utility of various forms of input structural data for design. To facilitate a more thorough analysis, we developed new methods for the design and high-throughput stability determination of combinatorial mutation libraries based on protein design calculations. The application of these methods to the core design of a small model system produced many variants with improved thermodynamic stability and showed that multistate design methods can be readily applied to large structural ensembles. We found that exhaustive screening of our designed libraries helped to clarify several sources of simulation error that would have otherwise been difficult to ascertain. Interestingly, the lack of correlation between our simulated and experimentally measured stability values shows clearly that a design procedure need not reproduce experimental data exactly to achieve success. This surprising result suggests potentially fruitful directions for the improvement of computational protein design technology.

‣ Genomic analysis, cytokine expression, and microRNA profiling reveal biomarkers of human dietary zinc depletion and homeostasis

Ryu, Moon-Suhn; Langkamp-Henken, Bobbi; Chang, Shou-Mei; Shankar, Meena N.; Cousins, Robert J.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Implementation of zinc interventions for subjects suspected of being zinc-deficient is a global need, but is limited due to the absence of reliable biomarkers. To discover molecular signatures of human zinc deficiency, a combination of transcriptome, cytokine, and microRNA analyses was applied to a dietary zinc depletion/repletion protocol with young male human subjects. Concomitant with a decrease in serum zinc concentration, changes in buccal and blood gene transcripts related to zinc homeostasis occurred with zinc depletion. Microarray analyses of whole blood RNA revealed zinc-responsive genes, particularly, those associated with cell cycle regulation and immunity. Responses of potential signature genes of dietary zinc depletion were further assessed by quantitative real-time PCR. The diagnostic properties of specific serum microRNAs for dietary zinc deficiency were identified by acute responses to zinc depletion, which were reversible by subsequent zinc repletion. Depression of immune-stimulated TNFα secretion by blood cells was observed after low zinc consumption and may serve as a functional biomarker. Our findings introduce numerous novel candidate biomarkers for dietary zinc status assessment using a variety of contemporary technologies and which identify changes that occur prior to or with greater sensitivity than the serum zinc concentration which represents the current zinc status assessment marker. In addition...

‣ Cyclic strain induces dual-mode endothelial-mesenchymal transformation of the cardiac valve

Balachandran, Kartik; Alford, Patrick W.; Wylie-Sears, Jill; Goss, Josue A.; Grosberg, Anna; Bischoff, Joyce; Aikawa, Elena; Levine, Robert A.; Parker, Kevin Kit
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Endothelial-mesenchymal transformation (EMT) is a critical event for the embryonic morphogenesis of cardiac valves. Inducers of EMT during valvulogenesis include VEGF, TGF-β1, and wnt/β-catenin (where wnt refers to the wingless-type mammary tumor virus integration site family of proteins), that are regulated in a spatiotemporal manner. EMT has also been observed in diseased, strain-overloaded valve leaflets, suggesting a regulatory role for mechanical strain. Although the preponderance of studies have focused on the role of soluble mitogens, we asked if the valve tissue microenvironment contributed to EMT. To recapitulate these microenvironments in a controlled, in vitro environment, we engineered 2D valve endothelium from sheep valve endothelial cells, using microcontact printing to mimic the regions of isotropy and anisotropy of the leaflet, and applied cyclic mechanical strain in an attempt to induce EMT. We measured EMT in response to both low (10%) and high strain (20%), where low-strain EMT occurred via increased TGF-β1 signaling and high strain via increased wnt/β-catenin signaling, suggesting dual strain-dependent routes to distinguish EMT in healthy versus diseased valve tissue. The effect was also directionally dependent...

‣ Droplet microfluidics driven by gradients of confinement

Dangla, Rémi; Kayi, S. Cagri; Baroud, Charles N.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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The miniaturization of droplet manipulation methods has led to drops being proposed as microreactors in many applications of biology and chemistry. In parallel, microfluidic methods have been applied to generate monodisperse emulsions for applications in the pharmaceuticals, cosmetics, and food industries. To date, microfluidic droplet production has been dominated by a few designs that use hydrodynamic forces, resulting from the flowing fluids, to break drops at a junction. Here we present a platform for droplet generation and manipulation that does not depend on the fluid flows. Instead, we use devices that incorporate height variations to subject the immiscible interfaces to gradients of confinement. The resulting curvature imbalance along the interface causes the detachment of monodisperse droplets, without the need for a flow of the external phase. Once detached, the drops are self-propelled due to the gradient of surface energy. We show that the size of the drops is determined by the device geometry; it is insensitive to the physical fluid properties and depends very weakly on the flow rate of the dispersed phase. This allows us to propose a geometric theoretical model that predicts the dependence of droplet size on the geometric parameters...

‣ Using model-based functional MRI to locate working memory updates and declarative memory retrievals in the fronto-parietal network

Borst, Jelmer P.; Anderson, John R.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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In this study, we used model-based functional MRI (fMRI) to locate two functions of the fronto-parietal network: declarative memory retrievals and updating of working memory. Because regions in the fronto-parietal network are by definition coherently active, locating functions within this network is difficult. To overcome this problem, we applied model-based fMRI, an analysis method that uses predictions of a computational model to inform the analysis. We applied model-based fMRI to five previously published datasets with associated computational cognitive models, and subsequently integrated the results in a meta-analysis. The meta-analysis showed that declarative memory retrievals correlated with activity in the inferior frontal gyrus and the anterior cingulate, whereas updating of working memory corresponded to activation in the inferior parietal lobule, as well as to activation around the inferior frontal gyrus and the anterior cingulate.

‣ Elasticity, structure, and relaxation of extended proteins under force

Stirnemann, Guillaume; Giganti, David; Fernandez, Julio M.; Berne, B. J.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Force spectroscopies have emerged as a powerful and unprecedented tool to study and manipulate biomolecules directly at a molecular level. Usually, protein and DNA behavior under force is described within the framework of the worm-like chain (WLC) model for polymer elasticity. Although it has been surprisingly successful for the interpretation of experimental data, especially at high forces, the WLC model lacks structural and dynamical molecular details associated with protein relaxation under force that are key to the understanding of how force affects protein flexibility and reactivity. We use molecular dynamics simulations of ubiquitin to provide a deeper understanding of protein relaxation under force. We find that the WLC model successfully describes the simulations of ubiquitin, especially at higher forces, and we show how protein flexibility and persistence length, probed in the force regime of the experiments, are related to how specific classes of backbone dihedral angles respond to applied force. Although the WLC model is an average, backbone model, we show how the protein side chains affect the persistence length. Finally, we find that the diffusion coefficient of the protein’s end-to-end distance is on the order of 108 nm2/s...

‣ Exogenous gypsy insulator sequences modulate transgene expression in the malaria vector mosquito, Anopheles stephensi

Carballar-Lejarazú, Rebeca; Jasinskiene, Nijole; James, Anthony A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Malaria parasites are transmitted to humans by mosquitoes of the genus Anopheles, and these insects are the targets of innovative vector control programs. Proposed approaches include the use of genetic strategies based on transgenic mosquitoes to suppress or modify vector populations. Although substantial advances have been made in engineering resistant mosquito strains, limited efforts have been made in refining mosquito transgene expression, in particular attenuating the effects of insertions sites, which can result in variations in phenotypes and impacts on fitness due to the random integration of transposon constructs. A promising strategy to mitigate position effects is the identification of insulator or boundary DNA elements that could be used to isolate transgenes from the effects of their genomic environment. We applied quantitative approaches that show that exogenous insulator-like DNA derived from the Drosophila melanogaster gypsy retrotransposon can increase and stabilize transgene expression in transposon-mediated random insertions and recombinase-catalyzed, site-specific integrations in the malaria vector mosquito, Anopheles stephensi. These sequences can contribute to precise expression of transgenes in mosquitoes engineered for both basic and applied goals.

‣ Matrix-dependent adhesion mediates network responses to physiological stimulation of the osteocyte cell process

Wu, Danielle; Schaffler, Mitchell B.; Weinbaum, Sheldon; Spray, David C.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Osteocytes are bone cells that form cellular networks that sense mechanical loads distributed throughout the bone tissue. Interstitial fluid flow in the lacunar canalicular system produces focal strains at localized attachment sites around the osteocyte cell process. These regions of periodic attachment between the osteocyte cell membrane and its canalicular wall are sites where pN-level fluid-flow induced forces are generated in vivo. In this study, we show that focally applied forces of this magnitude using a newly developed Stokesian fluid stimulus probe initiate rapid and transient intercellular electrical signals in vitro. Our experiments demonstrate both direct gap junction coupling and extracellular purinergic P2 receptor signaling between MLO-Y4 cells in a connected bone cell network. Intercellular signaling was initiated by pN-level forces applied at integrin attachment sites along both appositional and distal unapposed cell processes, but not initiated at their cell bodies with equivalent forces. Electrical coupling was evident in 58% of all cell pairs tested with appositional connections; coupling strength increased with the increasing number of junctional connections. Apyrase, a nucleotide-degrading enzyme, suppressed and abolished force-induced effector responses...

‣ Convex lens-induced nanoscale templating

Berard, Daniel J.; Michaud, François; Mahshid, Sara; Ahamed, Mohammed Jalal; McFaul, Christopher M. J.; Leith, Jason S.; Bérubé, Pierre; Sladek, Rob; Reisner, Walter; Leslie, Sabrina R.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Convex lens-induced nanoscale templating (CLINT) represents a conceptual breakthrough in nanofluidic technology for single-molecule manipulation. CLINT solves a key challenge faced by the nanofluidics field by bridging the multiple-length scales required to efficiently bring single-molecule analytes from the pipette tip to the nanofluidic channel. To do this, CLINT loads single-molecule analytes into embedded nanofeatures via dynamic control of applied vertical confinement, which we have demonstrated by loading and extending DNA within nanochannels. CLINT offers unique advantages in single-molecule DNA mapping by facilitating surface passivation, increasing loading efficiency, obviating the need for applied pressure or electric fields, and enhancing compatibility with physiological buffers and long DNA molecules extracted from complex genomes.

‣ Crop rotations in the sea: Increasing returns and reducing risk of collapse in sea cucumber fisheries

Plagányi, Éva Elizabeth; Skewes, Timothy; Murphy, Nicole; Pascual, Ricardo; Fischer, Mibu
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Rotating the harvest of natural resources is a management strategy that humans have used on land for centuries, but it is less commonly applied to marine resources. Marine animals, such as sea cucumbers, scallops, and abalone, may be particularly suited for this form of management. Although highly important to many communities worldwide, they are often severely overexploited, underlining the need for effective and easy to manage harvest strategies. We modeled the rotational zone strategy applied to the multispecies sea cucumber fishery in Australia’s Great Barrier Reef Marine Park and show a substantial reduction in the risk of localized depletion, higher long-term yields, and improved economic performance. Hence, our results support the use of rotational harvests to better manage these marine resources.

‣ Exact results with the J-integral applied to free-boundary flows

Ben Amar, Martine; Rice, James R.
Fonte: Cambridge University Press Publicador: Cambridge University Press
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We apply the J-integral to free-boundary flows in a channel geometry such as viscous fingering or blob injection in Hele-Shaw cells, void propagation in electromigration, and injection of air bubbles into inviscid liquids. The theory of that and related conservation integrals, developed in elasticity, is outlined in a way that is applicable to fluid mechanics problems. Depending on the boundary conditions, for infinite bubbles in Laplacian fields we are able to use the J-integral to predict finger width if such solutions exist or to predict that there are no solutions. For finite sized bubbles, bounds can sometimes be derived. In the case of Hele-Shaw flows, in which solutions appear as a continuum, finger width cannot be constrained, but we do obtain a new derivation and generalization of Richardson moment conservation. Applications to vortex motion are also outlined briefly.; Earth and Planetary Sciences; Engineering and Applied Sciences

‣ Direct Structural Observation of a Molecular Junction by High-Energy X-Ray Reflectometry

Lefenfeld, Michael; Baumert, Julian; Sloutskin, Eli; Kuzmenko, Ivan; Pershan, Peter S.; Deutsch, Moshe; Nuckolls, Colin; Ocko, Benjamin M.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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We report a direct angstrom resolution measurement of the structure of a molecular-size electronic junction comprising a single (or a double) layer of alkyl-thiol and alkyl-silane molecules at the buried interface between solid silicon and liquid mercury. The high-energy synchrotron x-ray measurements reveal densely packed layers comprising roughly interface-normal molecules. The monolayer’s thickness is found to be 3–4 Å larger than that of similar layers at the free surfaces of both mercury and silicon. The origins of this and the other unusual features detected are discussed in this article. Measurements of the bilayer junction with an applied potential did not show visible changes in the surface normal structure.; Engineering and Applied Sciences

‣ Non-negative matrix decomposition approaches to frequency domain analysis of music audio signals

Wood, Sean
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
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On étudie l’application des algorithmes de décomposition matricielles tel que la Factorisation Matricielle Non-négative (FMN), aux représentations fréquentielles de signaux audio musicaux. Ces algorithmes, dirigés par une fonction d’erreur de reconstruction, apprennent un ensemble de fonctions de base et un ensemble de coef- ficients correspondants qui approximent le signal d’entrée. On compare l’utilisation de trois fonctions d’erreur de reconstruction quand la FMN est appliquée à des gammes monophoniques et harmonisées: moindre carré, divergence Kullback-Leibler, et une mesure de divergence dépendente de la phase, introduite récemment. Des nouvelles méthodes pour interpréter les décompositions résultantes sont présentées et sont comparées aux méthodes utilisées précédemment qui nécessitent des connaissances du domaine acoustique. Finalement, on analyse la capacité de généralisation des fonctions de bases apprises par rapport à trois paramètres musicaux: l’amplitude, la durée et le type d’instrument. Pour ce faire, on introduit deux algorithmes d’étiquetage des fonctions de bases qui performent mieux que l’approche précédente dans la majorité de nos tests, la tâche d’instrument avec audio monophonique étant la seule exception importante.; We study the application of unsupervised matrix decomposition algorithms such as Non-negative Matrix Factorization (NMF) to frequency domain representations of music audio signals. These algorithms...

‣ Déploiement automatique d’une application de routage téléphonique d’une langue source vers une langue cible

Tremblay, Jérôme
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
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Les modèles de compréhension statistiques appliqués à des applications vocales nécessitent beaucoup de données pour être entraînés. Souvent, une même application doit pouvoir supporter plusieurs langues, c’est le cas avec les pays ayant plusieurs langues officielles. Il s’agit donc de gérer les mêmes requêtes des utilisateurs, lesquelles présentent une sémantique similaire, mais dans plusieurs langues différentes. Ce projet présente des techniques pour déployer automatiquement un modèle de compréhension statistique d’une langue source vers une langue cible. Ceci afin de réduire le nombre de données nécessaires ainsi que le temps relié au déploiement d’une application dans une nouvelle langue. Premièrement, une approche basée sur les techniques de traduction automatique est présentée. Ensuite une approche utilisant un espace sémantique commun pour comparer plusieurs langues a été développée. Ces deux méthodes sont comparées pour vérifier leurs limites et leurs faisabilités. L’apport de ce projet se situe dans l’amélioration d’un modèle de traduction grâce à l’ajout de données très proche de l’application ainsi que d’une nouvelle façon d’inférer un espace sémantique multilingue.; Statistical understanding models applied to dialog applications need a lot of training data. Often...