20,211 research outputs found

    On The Linguistic Effects Of Articulatory Ease, With A Focus On Sign Languages

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    Spoken language has a well-known drive for ease of articulation, which Kirchner (1998, 2004) analyzes as reduction of the total magnitude of all biomechanical forces involved. We extend Kirchner\u27s insights from vocal articulation to manual articulation, with a focus on joint usage, and we discuss ways that articulatory ease might be realized in sign languages. In particular, moving more joints and/or joints more proximal to the torso results in greater mass being moved, and thus more articulatory force being expended, than moving fewer joints or moving more distal joints. We predict that in casual conversation, where articulatory ease is prized, moving fewer joints should be favored over moving more, and moving distal joints should be favored over moving proximal joints. We report on the results of our study of the casual signing of fluent signers of American Sign Language, which confirm our predictions: in comparison to citation forms of signs, the casual variants produced by the signers in our experiment exhibit an overall decrease in average joint usage, as well as a general preference for more distal articulation than is used in citation form. We conclude that all language, regardless of modality, is shaped by a fundamental drive for ease of articulation. Our work advances a cross-modality approach for considering ease of articulation, develops a potentially important vocabulary for describing variations in signs, and demonstrates that American Sign Language exhibits variation that can be accounted for in terms of ease of articulation. We further suggest that the linguistic drive for ease of articulation is part of a broader tendency for the human body to reduce biomechanical effort in all physical activities

    Absolute absorption and fluorescence measurements over a dynamic range of 106^6 with cavity-enhanced laser-induced fluorescence

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    We describe a novel experimental setup that combines the advantages of both laser-induced fluorescence and cavity ring-down techniques. The simultaneous and correlated measurement of the ring-down and fluorescence signals yields absolute absorption coefficients for the fluorescence measurement. The combined measurement is conducted with the same sample in a single, pulsed laser beam. The fluorescence measurement extends the dynamic range of a stand-alone cavity ring-down setup from typically three to at least six orders of magnitude. The presence of the cavity improves the quality of the signal, in particular the signal-to-noise ratio. The methodology, dubbed cavity-enhanced laser-induced fluorescence (CELIF), is developed and rigorously tested against the spectroscopy of 1,4-bis(phenylethynyl)benzene in a molecular beam and density measurements in a cell. We outline how the method can be utilised to determine absolute quantities: absorption cross sections, sample densities and fluorescence quantum yields.Comment: 12 pages, 6 figures, submitted to J. Chem. Phy

    A Bulk-Parallel Priority Queue in External Memory with STXXL

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    We propose the design and an implementation of a bulk-parallel external memory priority queue to take advantage of both shared-memory parallelism and high external memory transfer speeds to parallel disks. To achieve higher performance by decoupling item insertions and extractions, we offer two parallelization interfaces: one using "bulk" sequences, the other by defining "limit" items. In the design, we discuss how to parallelize insertions using multiple heaps, and how to calculate a dynamic prediction sequence to prefetch blocks and apply parallel multiway merge for extraction. Our experimental results show that in the selected benchmarks the priority queue reaches 75% of the full parallel I/O bandwidth of rotational disks and and 65% of SSDs, or the speed of sorting in external memory when bounded by computation.Comment: extended version of SEA'15 conference pape

    Study of an auroral zone rocket experiment Final report

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    Measurement of flux and energy spectra of protons, energetic particles, hydrogen atoms, and electrons in auroral zone by Nike-Tomahawk sounding rocke

    Persistence effects in deterministic diffusion

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    In systems which exhibit deterministic diffusion, the gross parameter dependence of the diffusion coefficient can often be understood in terms of random walk models. Provided the decay of correlations is fast enough, one can ignore memory effects and approximate the diffusion coefficient according to dimensional arguments. By successively including the effects of one and two steps of memory on this approximation, we examine the effects of ``persistence'' on the diffusion coefficients of extended two-dimensional billiard tables and show how to properly account for these effects, using walks in which a particle undergoes jumps in different directions with probabilities that depend on where they came from.Comment: 7 pages, 7 figure

    Local incompatibility of the microlocal spectrum condition with the KMS property along spacelike directions in quantum field theory on curved spacetime

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    States of a generic quantum field theory on a curved spacetime are considered which satisfy the KMS condition with respect to an evolution associated with a complete (Killing) vector field. It is shown that at any point where the vector field is spacelike, such states cannot satisfy a certain microlocal condition which is weaker than the microlocal spectrum condition in the case of asymptotically free fields

    Stabilisation of fluvial bed sediments by invasive quagga mussels (Dreissena bugensis)

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    River gravel mobility is an important control on river behaviour, morphology, and ecosystem processes. Gravel stability is dependent on abiotic flow and sediment properties, alongside less widely acknowledged biotic processes. The quagga mussel (Dreissena bugensis), a highly invasive bivalve, frequently occurs at high population densities in rivers and lakes. Quagga mussels attach to benthic sediments using byssal threads, which might affect sediment stability and thereby broader river geomorphology. We aimed to (1) characterise controls of quagga mussel sediment attachment by conducting a field survey in an invaded river, (2) investigate resultant changes in the critical shear stress needed to entrain fluvial bed materials via an ex-situ flume experiment, for measured average (135 m-2) and potential future (270 m-2) mussel densities, and (3) model how this may affect sediment transport rates. From field surveys, mean quagga mussel density was 122 m 2, attaching to an average of 591 g m 2 of mineral bed sediments. Across the survey reach, mussels attached to all grain sizes available, with attachment driven by grain availability, rather than active selection of particular grain sizes. In the ex-situ flume experiment, densities of 135 mussels m-2 did not significantly increase the critical shear stress of fluvial bed materials, but a density of 270 mussels m-2 significantly increased critical shear stress by 40%. Estimates of the proportion of time these critical stresses are exceeded at the field site indicated high densities of quagga mussels may reduce the occurrence of a geomorphically active flood event from Q30 to Q2. These results present feasible invasion scenarios, as quagga mussels frequently reach benthic densities orders of magnitude greater than observed here. This study indicates that substantial alterations to bedload sediment transport may occur following quagga mussel invasion. Future geomorphic modelling should include biology to better understand rates and processes of landscape development

    Eddington-Born-Infeld action for dark energy and dark matter

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    We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the Born-Infeld field has an equation of state which interpolates between matter, w=0 (small times), and a cosmological constant w=-1 (large times). On galactic scales, the Born-Infeld field predicts asymptotically flat rotation curves.Comment: A sign mistake in section on galactic scales is pointed out. This sign invalidates the content of that section. See comment on manuscrip

    Why crime prevention strategies may be effective against both deliberate and impulsive burglars.

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    Not all those who commit burglary offenses do so for the same reasons – some are deliberate, planning their actions, while others are more impulsive. In new research on patterns of opportunism among burglars, Amber N. Sanders, Joseph B. Kuhns, and Kristie R. Blevins find that deliberate burglars are more motivated by money, while impulsive burglars were motivated by drugs and/or money. They suggest that burglars of both types may be dissuaded by crime prevention measures which might make their actions riskier
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