13,571 research outputs found

    ASR decoding in a computational model of human word recognition

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    This paper investigates the interaction between acoustic scores and symbolic mismatch penalties in multi-pass speech decoding techniques that are based on the creation of a segment graph followed by a lexical search. The interaction between acoustic and symbolic mismatches determines to a large extent the structure of the search space of these multipass approaches. The background of this study is a recently developed computational model of human word recognition, called SpeM. SpeM is able to simulate human word recognition data and is built as a multi-pass speech decoder. Here, we focus on unravelling the structure of the search space that is used in SpeM and similar decoding strategies. Finally, we elaborate on the close relation between distances in this search space, and distance measures in search spaces that are based on a combination of acoustic and phonetic features

    A limit on behavioral plasticity in speech perception.

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    It is well attested that we perceive speech through the filter of our native language: a classic example is that of Japanese listeners who cannot discriminate between the American /l/ and /r/ and identify both as their own /r/ phoneme (Goto, 1971). Studies in the laboratory have shown, however, that perception of non-native speech sounds can be learned through training (Lively, Pisoni, Yamada, & Tohkura, 1994). This is consistent with neurophysiological evidence showing considerable experience-dependent plasticity in the brain at the first levels of sensory processing (Edeline & Weinberger, 1993; Kraus, et al., 1995; Merzenich & Sameshima, 1993; Weinberger, 1993). Outside of the laboratory, however, the situation seems to differ: we here report a study involving Spanish-Catalan bilingual subjects who have had the best opportunities to learn a new contrast but did not do it. Our study demonstrates a striking lack of behavioral plasticity: early and extensive exposure to a second language is not sufficient to attain the ultimate phonological competence of native speakers

    THE FARM LEVEL EFFECTS OF BETTER ACCESS TO INFORMATION: THE CASE OF DART

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    In this study, two methods of entering and accessing dairy herd records are compared: the traditional mail-in Dairy Herd Improvement (DHI) system and the Direct Access to Records by Telephone (DART) system, which provides more timely and convenient access to records. An evaluation of DART was carried out using mail survey responses from 117 DART users and telephone surveys of 40 randomly selected users. Results indicate that DART users are generally satisfied with the system and feel that it improves their herd management. Variations in use of the DART system by DART users are explained by herd, cost, and management variables. DART users and comparable non-DART, DHI users are compared with respect to gains in herd production efficiency. Results indicate that DART users made somewhat better gains in most efficiency measures but that the differences were generally not statistically significant.Farm Management,

    A deep dive into NGC 604 with Gemini/NIRI imaging

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    The giant HII region NGC 604 constitutes a complex and rich population to studying detail many aspects of massive star formation, such as their environments and physical conditions, the evolutionary processes involved, the initial mass function for massive stars and star-formation rates, among many others. Here, we present our first results of a near-infrared study of NGC 604 performed with NIRI images obtained with Gemini North. Based on deep JHK photometry, 164 sources showing infrared excess were detected, pointing to the places where we should look for star-formation processes currently taking place. In addition, the color-color diagram reveals a great number of objects that could be giant/supergiant stars or unresolved, small, tight clusters. A extinction map obtained based on narrow-band images is also shown.Comment: 4 pages, 4 figures. To appear in the proceedings of IAU Symposium 266, Star Clusters: Basic Galactic Building Blocks Throughout Time and Space, eds. R. de Grijs and J. Lepin

    Collective non-thermal emission from an extragalactic jet interacting with stars

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    The central regions of galaxies are complex environments, rich in evolved and/or massive stars. For galaxies hosting an active galactic nucleus (AGN) with jets, the interaction of the jets with the winds of the stars within can lead to particle acceleration, and to extended high-energy emitting regions. We compute the non-thermal emission produced by the jet flow shocked by stellar winds on the jet scale, far from the jet-star direct interaction region. First, prescriptions for the winds of the relevant stellar populations in different types of galaxies are obtained. The scenarios adopted include galaxies with their central regions dominated by old or young stellar populations, and with jets of different power. Then, we estimate the available energy to accelerate particles in the jet shock, and compute the transport and energy evolution of the accelerated electrons, plus their synchrotron and inverse Compton emission, in the shocked flow along the jet. A significant fraction of the jet energy, ∼0.1−10\sim 0.1-10\%, can potentially be available for the particles accelerated in jet-wind shocks in the studied cases. The non-thermal particles can produce most of the high-energy radiation on jet scales, far from the jet shock region. This high-energy emission will be strongly enhanced in jets aligned with the line of sight due to Doppler boosting effects. The interaction of relativistic jets with stellar winds may contribute significantly to the persistent high-energy emission in some AGNs with jets. However, in the particular case of M87, this component seems too low to explain the observed gamma-ray fluxes.Comment: 15 pages, 11 figures. Accepted to be published in A&

    Eviction of a 125 GeV "heavy"-Higgs from the MSSM

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    We prove that the present experimental constraints are already enough to rule out the possibility of the ~125 GeV Higgs found at LHC being the second lightest Higgs in a general MSSM context, even with explicit CP violation in the Higgs potential. Contrary to previous studies, we are able to eliminate this possibility analytically, using simple expressions for a relatively small number of observables. We show that the present LHC constraints on the diphoton signal strength, tau-tau production through Higgs and BR(B -> X_s gamma) are enough to preclude the possibility of H_2 being the observed Higgs with m_H~125 GeV within an MSSM context, without leaving room for finely tuned cancellations. As a by-product, we also comment on the difficulties of an MSSM interpretation of the excess in the gamma-gamma production cross section recently found at CMS that could correspond to a second Higgs resonance at m_H~136 GeV.Comment: 38 pages, 9 figures. Final version accepted at JHEP. Sections 2, 3 and appendices simplified. Experimental results updated, several references added. Small typos corrected and a new comparison of approximate formulas with full expressions include

    "Bridging the Musical and Scriptural Generation Gap": The Jesus People Movement and Jesus Christ Superstar

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    Jesus Christ Superstar, a "rock opera" written by Andrew Lloyd Webber and Tim Rice and first staged in 1971, enjoyed a significant amount of popularity in the United States at the end of the "long sixties" era. However, American Christians were divided in their reactions to the fusion of religion and popular culture in Superstar: supporters hailed the piece as a means to reawaken interest in Christianity among a disillusioned youth generation, but detractors criticized the work as "sacrilegious" and "irreverent." At the same time Superstar entered the American public eye, the Jesus People Movement (ca 1967-1974), an unprecedented Christian revival among youth, was gaining momentum and spreading eastward from California. Like Superstar, the Jesus People blended Christian practice and narrative with vernacular culture in a manner that had a polarizing effect among contemporary Christians. This study contextualizes Superstar with the Jesus People Movement in order to examine how the moment in American religious history at the end of the long sixties created the conditions for Superstar to become both popular and controversial

    The mineralogy and chemistry of pulverised fuel ash produced by three South African coal-burning power stations

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    Bibliography: pages 161-166.The chemical and mineral compositions are presented for 63 pulverized fuel ash (PFA) and 16 input coal samples collected from Lethabo, Duvha and Matla power stations over the period 1987-1988. Bulk chemical composition was determined by X-ray fluorescence spectrometry. The mineral concentrations were determined by semi-quantitative X-ray diffraction based on integrated counts over peak areas, with silicon used as an internal standard. The particle size distributions were determined for two sample sets from each power station with a Malvern Instruments Particle Sizer. The major phases present in the ash are glass ( 45-75% ), mullite (16-39%) and quartz (1.5-16% ). The quartz concentration decreases in PF A from fields 1 to 4 in all the stations, and is positively correlated with the SiO₂ concentration. The concentrations of glass, mullite and quartz in PFA generally vary within well defined limits which remain constant with time. An exception is the glass concentration in Duvha PFA. Spinel concentration generally decreases in concentration in PFA from fields 1 to 4, and is positively correlated with the Fe₂O₃ concentration. Of the trace elements determined, Zr, Rb and Mn generally have no or very low enrichment in concentration in PFA from fields 1 to 4. The highest enrichment factors ( > 5) were found for As, Ge and Se in Duvha PF A. The composition of the glass and ferrite spinel phases were determined by electron microprobe analysis. The glass consists of SiO₂ (21-100%) and Al₂ O₃ (0.1-49%), with significant proportions of CaO, TiO₂, Fe₂O₃ and MgO. Al₂O₃ , MgO and TiO₂ substitute for FeO in the spinel structure, with MgO substitution dominant in Duvha spinels. Chemical mass balance calculations suggest that of the elements determined for Lethabo PFA, the only one released in a significant proportion to the atmosphere is S(92% )

    Information encoding by deep neural networks: what can we learn?

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    The recent advent of deep learning techniques in speech tech-nology and in particular in automatic speech recognition hasyielded substantial performance improvements. This suggeststhat deep neural networks (DNNs) are able to capture structurein speech data that older methods for acoustic modeling, suchas Gaussian Mixture Models and shallow neural networks failto uncover. In image recognition it is possible to link repre-sentations on the first couple of layers in DNNs to structuralproperties of images, and to representations on early layers inthe visual cortex. This raises the question whether it is possi-ble to accomplish a similar feat with representations on DNNlayers when processing speech input. In this paper we presentthree different experiments in which we attempt to untanglehow DNNs encode speech signals, and to relate these repre-sentations to phonetic knowledge, with the aim to advance con-ventional phonetic concepts and to choose the topology of aDNNs more efficiently. Two experiments investigate represen-tations formed by auto-encoders. A third experiment investi-gates representations on convolutional layers that treat speechspectrograms as if they were images. The results lay the basisfor future experiments with recursive networks
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