59,534 research outputs found

    The refractive characteristics and intraocular tensions of colony chimpanzees Technical report, Aug. 1965

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    Refraction and intraocular pressure tests of colony chimpanzees - age relationshi

    Ultrasound and phakometry measurements of the primate eye Technical report, Aug. 1965

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    Ultrasonic testing and phakometry measurements of primate ey

    Stochastic Language Generation in Dialogue using Recurrent Neural Networks with Convolutional Sentence Reranking

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    The natural language generation (NLG) component of a spoken dialogue system (SDS) usually needs a substantial amount of handcrafting or a well-labeled dataset to be trained on. These limitations add significantly to development costs and make cross-domain, multi-lingual dialogue systems intractable. Moreover, human languages are context-aware. The most natural response should be directly learned from data rather than depending on predefined syntaxes or rules. This paper presents a statistical language generator based on a joint recurrent and convolutional neural network structure which can be trained on dialogue act-utterance pairs without any semantic alignments or predefined grammar trees. Objective metrics suggest that this new model outperforms previous methods under the same experimental conditions. Results of an evaluation by human judges indicate that it produces not only high quality but linguistically varied utterances which are preferred compared to n-gram and rule-based systems.Comment: To be appear in SigDial 201

    Subsurface microstructural changes in a cast heat resisting alloy caused by high temperature corrosion

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    A cast HP ModNb alloy (Fe–25Cr–35Ni–1Nb, wt.%) was oxidised and carburised in CO–CO2 corresponding to aC = 0.1 and pO2 = 3 1016 atm at 1080 C. Formation of an external, chromium-rich oxide scale led to depletion of this metal in a deep alloy subsurface zone. Within that zone, secondary chromium-rich carbides dissolved, primary carbides oxidised, solute silicon and aluminium internally oxidised, and extensive porosity developed. Pore volumes correspond to the difference between metal loss by scaling and metal displacement by internal oxidation, assuming the scale–metal interface to be fixed. The pores are concluded to be Kirkendall void

    Uniform Silicon Isotope Ratios Across the Milky Way Galaxy

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    We report the relative abundances of the three stable isotopes of silicon, 28^{28}Si, 29^{29}Si and 30^{30}Si, across the Galaxy using the v=0,J=10v = 0, J = 1 \to 0 transition of silicon monoxide. The chosen sources represent a range in Galactocentric radii (RGCR_{\rm GC}) from 0 to 9.8 kpc. The high spectral resolution and sensitivity afforded by the GBT permit isotope ratios to be corrected for optical depths. The optical-depth-corrected data indicate that the secondary-to-primary silicon isotope ratios 29Si/28Si^{29}{\rm Si}/^{28}{\rm Si} and 30Si/28Si^{30}{\rm Si}/^{28}{\rm Si} vary much less than predicted on the basis of other stable isotope ratio gradients across the Galaxy. Indeed, there is no detectable variation in Si isotope ratios with RGCR_{\rm GC}. This lack of an isotope ratio gradient stands in stark contrast to the monotonically decreasing trend with RGCR_{\rm GC} exhibited by published secondary-to-primary oxygen isotope ratios. These results, when considered in the context of the expectations for chemical evolution, suggest that the reported oxygen isotope ratio trends, and perhaps that for carbon as well, require further investigation. The methods developed in this study for SiO isotopologue ratio measurements are equally applicable to Galactic oxygen, carbon and nitrogen isotope ratio measurements, and should prove useful for future observations of these isotope systems.Comment: 18 pages, 12 figures, 2 tables. Published in The Astrophysical Journal, Volume 839, Issue

    Far-infrared imaging of tokamak plasma

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    A 20-channel interferometer has been developed which utilizes a linear, one-dimensional microbolometer array to obtain single-shot density profiles from the UCLA Microtor tokamak plasma. The interferometer has been used to study time-dependent phenomena in the plasma density profile. Observations of the sawtooth instability clearly show the growth of the m=0 mode from a localized oscillation (r=1 cm) on axis to an oscillation of the entire plasma. Also, measurements during the initial startup phase of the discharge show evidence of hollow density profiles. In addition, a simultaneous measurement of the poloidal magnetic field has been developed which provides 20 channels of polarimetry. Interferometry and polarimetry both use the same imaging system and the spatial resolution of both measurements has been tested using plastic and crystal-quartz test objects. The signal-to-noise ratio for the polarimeter has also proved adequate for the expected Faraday rotation angle (alphamax=7°, Ip=70 kA, n=5×10^13 cm^−3)

    Blind Normalization of Speech From Different Channels

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    We show how to construct a channel-independent representation of speech that has propagated through a noisy reverberant channel. This is done by blindly rescaling the cepstral time series by a non-linear function, with the form of this scale function being determined by previously encountered cepstra from that channel. The rescaled form of the time series is an invariant property of it in the following sense: it is unaffected if the time series is transformed by any time-independent invertible distortion. Because a linear channel with stationary noise and impulse response transforms cepstra in this way, the new technique can be used to remove the channel dependence of a cepstral time series. In experiments, the method achieved greater channel-independence than cepstral mean normalization, and it was comparable to the combination of cepstral mean normalization and spectral subtraction, despite the fact that no measurements of channel noise or reverberations were required (unlike spectral subtraction).Comment: 25 pages, 7 figure

    Quantum paramagnetic ground states on the honeycomb lattice and field-induced transition to N\'eel order

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    Motivated by recent experiments on Bi3_3Mn4_4O12_{12}(NO3_3), and a broader interest arising from numerical work on the honeycomb lattice Hubbard model, we have studied the effect of a magnetic field on honeycomb lattice spin models with quantum paramagnetic ground states. For a model with frustrating second-neighbor exchange, J2J_2, we use a Lindemann-like criterion within spin wave theory to show that N\'eel order melts beyond a critical J2J_2. The critical J2J_2 increases with a magnetic field, implying the existence of a field-induced paramagnet-N\'eel transition over a range of J2J_2. We also study bilayer model using a spin-SS generalization of bond operator mean field theory. We show that there is a N\'eel-dimer transition for various spin values with increasing bilayer coupling, and that the resulting interlayer dimer state undergoes a field induced transition into a state with transverse N\'eel order. Finally, we study a spin-3/2 model which interpolates between the Heisenberg model and the Affleck-Kennedy-Lieb-Tasaki (AKLT) parent Hamiltonian. Using exact diagonalization, we compute the fidelity susceptibility to locate the Neel-AKLT quantum critical point, obtain the spin gap of the AKLT parent Hamiltonian, and argue that AKLT state also undergoes field-induced Neel ordering.Comment: 8 pages, revised longer version of arXiv:1012.0316. Corrected factor of 2 error in Eq.[16], replotted Fig.[4] and revised the critical Jc/J1J_c/J_1 needed to stabilize interlayer dimer state. We thank S. V. Isakov for discussions which uncovered this erro

    The K-Server Dual and Loose Competitiveness for Paging

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    This paper has two results. The first is based on the surprising observation that the well-known ``least-recently-used'' paging algorithm and the ``balance'' algorithm for weighted caching are linear-programming primal-dual algorithms. This observation leads to a strategy (called ``Greedy-Dual'') that generalizes them both and has an optimal performance guarantee for weighted caching. For the second result, the paper presents empirical studies of paging algorithms, documenting that in practice, on ``typical'' cache sizes and sequences, the performance of paging strategies are much better than their worst-case analyses in the standard model suggest. The paper then presents theoretical results that support and explain this. For example: on any input sequence, with almost all cache sizes, either the performance guarantee of least-recently-used is O(log k) or the fault rate (in an absolute sense) is insignificant. Both of these results are strengthened and generalized in``On-line File Caching'' (1998).Comment: conference version: "On-Line Caching as Cache Size Varies", SODA (1991

    Momentum transfer dependence of the proton's electric and magnetic polarizabilities

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    The Q^2-dependence of the sum of the electric and magnetic polarizabilities of the proton is calculated over the range 0 \leq Q^2 \leq 6 GeV^2 using the generalized Baldin sum rule. Employing a parametrization of the F_1 structure function valid down to Q^2 = 0.06 GeV^2, the polarizabilities at the real photon point are found by extrapolating the results of finite Q^2 to Q^2 = 0 GeV^2. We determine the evolution over four-momentum transfer to be consistent with the Baldin sum rule using photoproduction data, obtaining \alpha + \beta = 13.7 \pm 0.7 \times 10^{-4}\, \text{fm}^3.Comment: 4 pages, 3 figure
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