171 research outputs found

    Differentiated audio-tactile correspondences in sighted and blind individuals

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    The aim of the present study is to investigate whether the crossmodal correspondence robustly documented between auditory pitch and visual elevation has analogues in the audio-tactile domain. Across 4 experiments, the compatibility effects between intuitively congruent pairs of stimuli (i.e., outward tactile movement, going from the inside of the finger toward the fingertip and increasing pitch, or inward tactile movement and decreasing pitch) and incongruent pairs stimuli (i.e., the reverse associations) were measured. Two methods were compared to assess the behavioral effects of such a correspondence: One where participants have to respond to either the auditory or tactile stimulus presented simultaneously, while ignoring the other (speeded classification task), and the other where the auditory and tactile stimuli are presented sequentially and associated to different response buttons (implicit association test). No significant compatibility effect was observed under the speeded classification task. The implicit association test revealed a significant compatibility effect. This effect was similar in the conditions where the finger was placed vertically and horizontally. However, this implicit association between pitch and tactile movements was not observed in blind participants. These results have methodological implications for the explanation and testing of crossmodal correspondences, and the origin of the widely discussed association between pitch and vertical elevation

    Cosmology in massive gravity

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    We argue that more cosmological solutions in massive gravity can be obtained if the metric tensor and the tensor Σμν\Sigma_{\mu\nu} defined by St\"{u}ckelberg fields take the homogeneous and isotropic form. The standard cosmology with matter and radiation dominations in the past can be recovered and Λ\LambdaCDM model is easily obtained. The dynamical evolution of the universe is modified at very early times.Comment: 4 pages, 1 figure,add more reference

    Evaluation of the phase-aggression criterion for PIO detection in real-time

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    This paper presents the results of a pilot-in-the-loop experiment performed to investigate the efficacy of a pilot-induced oscillation (PIO) or adverse rotorcraft-pilot coupling (RPC) real-time detection method, to be implemented as an in-cockpit warning system. A test pilot performed a number of simulated flights inside the Heliflight-R simulator at the University of Liverpool. Two handling qualities (HQ) mission task element (MTE) maneuvers were chosen, namely Precision Hover and Lateral Reposition. The baseline dynamics were those of a FLIGHTLAB BO105-like helicopter model, as used in previous tests; changes in rate limits were introduced to induce the pilot-vehicle system (PVS) to be more RPC/PIO prone, and to observe pilot's adaptation to these variations causing system instabilities during the chosen MTEs. To objectively measure the severity of the PIO encountered during the tests, the Phase-Aggression Criterion (PAC) has been used. This method has been developed to allow for real-time PIO detection in order to provide the information inside the cockpit. In addition, pilot subjective ratings were collected, by using the HQs, PIO and Pilot Workload rating scales. Overall, the results show a good correlation between objective and subjective evaluations, and that it is possible to detect PIOs in real-time. The information can be provided to the pilot by means of visual, aural or haptic cues, which is the work the authors are currently carrying out

    On Internationalized Development Tendency of Art Gallery Education

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    内容摘要立足于21世纪,面对全球经济一体化的当代信息社会的变化,伴随传媒艺术信息网络技术的迅速发展与广泛应用,在教育已得到快速发展的今天,公民大众已不能仅仅满足于学校中学习,对校外社会教育需求增大,越发凸现美术馆教育的重要性是学校外社会教育的重要资源之一,也是实施社会教育的最佳场所。随着大众对文化艺术教育的重视,对文化艺术教育起支柱作用的美术馆教育得到认可,当代社会多元文化的背景要求美术馆教育功能进一步拓展,向美术馆教育国际化方向发展,充分吸取发达国家美术馆教育的实践经验,才能充分发挥美术馆教育所包含的促进国际理解,和体现通过艺术沟通多元文化的价值。所以美术馆教育向国际化发展趋势是必然的,美术...Abstract When it comes to the 21st century, with the rapid development of the current information society and the network technology in art information, the public can not only be satisfied with schooling, but more need to strengthen their need in social education off campus. It is generally acknowledged that art gallery education has become one of the important resources in off-campus ed...学位:文学硕士院系专业:艺术教育学院美术系_美术学学号:20032200

    Measuring the propagation speed of gravitational waves with LISA

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    The propagation speed of gravitational waves, cT , has been tightly constrained by the binary neutron star merger GW170817 and its electromagnetic counterpart, under the assumption of a frequency-independent cT . Drawing upon arguments from Effective Field Theory and quantum gravity, we discuss the possibility that modifications of General Relativity allow for transient deviations of cT from the speed of light at frequencies well below the band of current ground-based detectors. We motivate two representative Ansätze for cT (f), and study their impact upon the gravitational waveforms of massive black hole binary mergers detectable by the LISA mission. We forecast the constraints on cT (f) obtainable from individual systems and a population of sources, from both inspiral and a full inspiral-merger-ringdown waveform. We show that LISA will enable us to place stringent independent bounds on departures from General Relativity in unexplored low-frequency regimes, even in the absence of an electromagnetic counterpart

    Higher derivative theories with constraints : Exorcising Ostrogradski's Ghost

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    We prove that the linear instability in a non-degenerate higher derivative theory, the Ostrogradski instability, can only be removed by the addition of constraints if the original theory's phase space is reduced.Comment: 17 pages, no figures, version published in JCA

    Cosmological solutions of massive gravity on de Sitter

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    In the framework of the recently proposed models of massive gravity, defined with respect to a de Sitter reference metric, we obtain new homogeneous and isotropic solutions for arbitrary cosmological matter and arbitrary spatial curvature. These solutions can be classified into three branches. In the first two, the massive gravity terms behave like a cosmological constant. In the third branch, the massive gravity effects can be described by a time evolving effective fluid with rather remarkable features, including the property to behave as a cosmological constant at late time.Comment: 6 pages, 1 figure; discussion extended, a few references added, improved analysis in Section

    Exploring gravitational theories beyond Horndeski

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    We have recently proposed a new class of gravitational scalar-tensor theories free from Ostrogradski instabilities, in arXiv:1404.6495. As they generalize Horndeski theories, or "generalized" galileons, we call them G3^3. These theories possess a simple formulation when the time hypersurfaces are chosen to coincide with the uniform scalar field hypersurfaces. We confirm that they contain only three propagating degrees of freedom by presenting the details of the Hamiltonian formulation. We examine the coupling between these theories and matter. Moreover, we investigate how they transform under a disformal redefinition of the metric. Remarkably, these theories are preserved by disformal transformations that depend on the scalar field gradient, which also allow to map subfamilies of G3^3 into Horndeski theories.Comment: 33 pages, added comments and corrected typos as in JCAP versio

    Cosmological perturbations in Massive Gravity and the Higuchi bound

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    In de Sitter spacetime there exists an absolute minimum for the mass of a spin-2 field set by the Higuchi bound m^2 \geq 2H^2. We generalize this bound to arbitrary spatially flat FRW geometries in the context of the recently proposed ghost-free models of Massive Gravity with an FRW reference metric, by performing a Hamiltonian analysis for cosmological perturbations. We find that the bound generically indicates that spatially flat FRW solutions in FRW massive gravity, which exhibit a Vainshtein mechanism in the background as required by consistency with observations, imply that the helicity zero mode is a ghost. In contradistinction to previous works, the tension between the Higuchi bound and the Vainshtein mechanism is equally strong regardless of the equation of state for matter.Comment: 24 pages, typos and conventions correcte

    A Class of Effective Field Theory Models of Cosmic Acceleration

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    We explore a class of effective field theory models of cosmic acceleration involving a metric and a single scalar field. These models can be obtained by starting with a set of ultralight pseudo-Nambu-Goldstone bosons whose couplings to matter satisfy the weak equivalence principle, assuming that one boson is lighter than all the others, and integrating out the heavier fields. The result is a quintessence model with matter coupling, together with a series of correction terms in the action in a covariant derivative expansion, with specific scalings for the coefficients. After eliminating higher derivative terms and exploiting the field redefinition freedom, we show that the resulting theory contains nine independent free functions of the scalar field when truncated at four derivatives. This is in contrast to the four free functions found in similar theories of single-field inflation, where matter is not present. We discuss several different representations of the theory that can be obtained using the field redefinition freedom. For perturbations to the quintessence field today on subhorizon lengthscales larger than the Compton wavelength of the heavy fields, the theory is weakly coupled and natural in the sense of t'Hooft. The theory admits a regime where the perturbations become modestly nonlinear, but very strong nonlinearities lie outside its domain of validity.Comment: 43 pages, 2 figures; Version 3 publication versio
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