4,207 research outputs found

    Functional organization of human sensorimotor cortex for speech articulation.

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    Speaking is one of the most complex actions that we perform, but nearly all of us learn to do it effortlessly. Production of fluent speech requires the precise, coordinated movement of multiple articulators (for example, the lips, jaw, tongue and larynx) over rapid time scales. Here we used high-resolution, multi-electrode cortical recordings during the production of consonant-vowel syllables to determine the organization of speech sensorimotor cortex in humans. We found speech-articulator representations that are arranged somatotopically on ventral pre- and post-central gyri, and that partially overlap at individual electrodes. These representations were coordinated temporally as sequences during syllable production. Spatial patterns of cortical activity showed an emergent, population-level representation, which was organized by phonetic features. Over tens of milliseconds, the spatial patterns transitioned between distinct representations for different consonants and vowels. These results reveal the dynamic organization of speech sensorimotor cortex during the generation of multi-articulator movements that underlies our ability to speak

    Morphological operators for very low bit rate video coding

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    This paper deals with the use of some morphological tools for video coding at very low bit rates. Rather than describing a complete coding algorithm, the purpose of this paper is to focus on morphological connected operators and segmentation tools that have proved to be attractive for compression.Peer ReviewedPostprint (published version

    Guarding the Cold War Ramparts: The U.S. Navy\u27s Role in Continental Air Defense

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    Homeland defense was pushed to the top of the national security agenda when in August 1998 North Korea\u27s flight test of its Taep\u27o­ dong ballistic missile sparked a renewed debate over national missile defense. The Navy has become embroiled in that debate because its theater ballistic mis­ sile defense programs could provide a foundation for developing a sea-based national missile defense. It is seldom remembered that the Navy in the recent past took on a significant homeland defense mission-continental air defense. The Navy excelled at the continental air defense mission but found it difficult to reconcile with its other missions of sea control, power projection, and forward presence . That experience is worth examining as we contemplate our role in national defense today

    Accidents and Crises: Panay, Liberty, and Stark

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    Throughout the past decade there has been growing concern over the possibility of a Soviet-American war inadvertently triggered by escalatory processes resulting from unintentional or accidental actions or incidents. A spate of studies has examined these escalatory processes and the actions or incidents that might spark them

    No-arbitrage in discrete-time markets with proportional transaction costs and general information structure

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    We discuss the no-arbitrage conditions in a general framework for discrete-time models of financial markets with proportional transaction costs and general information structure. We extend the results of Kabanov and al. (2002), Kabanov and al. (2003) and Schachermayer (2004) to the case where bid-ask spreads are not known with certainty. In the "no-friction" case, we retrieve the result of Kabanov and Stricker (2003)

    Japan in Global Ocean Politics

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