40,685 research outputs found

    A binaural grouping model for predicting speech intelligibility in multitalker environments

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    Spatially separating speech maskers from target speech often leads to a large intelligibility improvement. Modeling this phenomenon has long been of interest to binaural-hearing researchers for uncovering brain mechanisms and for improving signal-processing algorithms in hearing-assistive devices. Much of the previous binaural modeling work focused on the unmasking enabled by binaural cues at the periphery, and little quantitative modeling has been directed toward the grouping or source-separation benefits of binaural processing. In this article, we propose a binaural model that focuses on grouping, specifically on the selection of time-frequency units that are dominated by signals from the direction of the target. The proposed model uses Equalization-Cancellation (EC) processing with a binary decision rule to estimate a time-frequency binary mask. EC processing is carried out to cancel the target signal and the energy change between the EC input and output is used as a feature that reflects target dominance in each time-frequency unit. The processing in the proposed model requires little computational resources and is straightforward to implement. In combination with the Coherence-based Speech Intelligibility Index, the model is applied to predict the speech intelligibility data measured by Marrone et al. The predicted speech reception threshold matches the pattern of the measured data well, even though the predicted intelligibility improvements relative to the colocated condition are larger than some of the measured data, which may reflect the lack of internal noise in this initial version of the model.R01 DC000100 - NIDCD NIH HH

    Impurity scattering in a d-wave superconductor

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    The influence of (non-magnetic and magnetic) impurities on the transition temperature of a d-wave superconductor is studied anew within the framework of BCS theory. Pairing interaction decreases linearly with the impurity concentration. Accordingly TcT_{c} suppression is proportional to the (potential or exchange) scattering rate, 1/Ï„1/\tau, due to impurities. The initial slope versus 1/Ï„1/\tau is found to depend on the superconductor contrary to Abrikosov-Gor'kov type theory. Near the critical impurity concentration TcT_{c} drops abruptly to zero. Because the potential scattering rate is generally much larger than the exchange scattering rate, magnetic impurities will also act as non-magnetic impurities as far as the TcT_{c} decrease is concerned. The implication for the impurity doping effect in high TcT_{c} superconductors is also discussed.Comment: 12 pages and 1 figure, PlainTex, submitted to Mod. Phys. Lett. B, For more information, please see "http://taesan.kaist.ac.kr/~yjkim

    Non-Markovian quantum state diffusion for an open quantum system in fermionic environments

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    Non-Markovian quantum state diffusion (NMQSD) provides a powerful approach to the dynamics of an open quantum system in bosonic environments. Here we develop an NMQSD method to study the open quantum system in fermionic environments. This problem involves anticommutative noise functions (i.e., Grassmann variables) that are intrinsically different from the noise functions of bosonic baths. We obtain the NMQSD equation for quantum states of the system and the non-Markovian master equation. Moreover, we apply this NMQSD method to single and double quantum-dot systems.Comment: 9 pages, 1 figur

    Character-level Chinese-English Translation through ASCII Encoding

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    Character-level Neural Machine Translation (NMT) models have recently achieved impressive results on many language pairs. They mainly do well for Indo-European language pairs, where the languages share the same writing system. However, for translating between Chinese and English, the gap between the two different writing systems poses a major challenge because of a lack of systematic correspondence between the individual linguistic units. In this paper, we enable character-level NMT for Chinese, by breaking down Chinese characters into linguistic units similar to that of Indo-European languages. We use the Wubi encoding scheme, which preserves the original shape and semantic information of the characters, while also being reversible. We show promising results from training Wubi-based models on the character- and subword-level with recurrent as well as convolutional models.Comment: 7 pages, 3 figures, 3rd Conference on Machine Translation (WMT18), 201

    Controlling Condensate Collapse and Expansion with an Optical Feshbach Resonance

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    We demonstrate control of the collapse and expansion of an 88Sr Bose-Einstein condensate using an optical Feshbach resonance (OFR) near the 1S0-3P1 intercombination transition at 689 nm. Significant changes in dynamics are caused by modifications of scattering length by up to +- ?10a_bg, where the background scattering length of 88Sr is a_bg = -2a0 (1a0 = 0.053 nm). Changes in scattering length are monitored through changes in the size of the condensate after a time-of-flight measurement. Because the background scattering length is close to zero, blue detuning of the OFR laser with respect to a photoassociative resonance leads to increased interaction energy and a faster condensate expansion, whereas red detuning triggers a collapse of the condensate. The results are modeled with the time-dependent nonlinear Gross-Pitaevskii equation.Comment: 5 pages, 3 figure

    A systematic study on the binding energy of Λ\Lambda hypernuclei

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    In this paper, we calculated the binding energy per baryon of the Λ\Lambda hypernuclei systemically, using the relativistic mean field theory (RMF) in a statistic frame. Some resemble properties are found among most of the hypernuclei found in experiments. The data show that a Λ\Lambda hypernucleus will be more stable, if it is composed of a Λ\Lambda hyperon adding to a stable normal nuclear core, or a Λ\Lambda hyperon replacing a neutron in a stable normal nuclear core. According to our calculations, existences of some new Λ\Lambda hypernuclei are predicted under the frame of RMF.Comment: 8 pages, 6 figures, 3 table

    Comparative study on growth and survival of larval and juvenile Dicentrarchus labrax rearing on rotifer and Artemia enriched with four different microalgae species

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    In the present study, two experiments were carried out, the first one at age from 4th to 24th days post hatching (dph) which include Dicentrarchus labrax larvae rearing on rotifer and Artemia enriched with four types of algae as follows: Chlorella salina, Dunaleilla salina, Nannochloropsis salina and Tetraselmis chuii (ch1, D1, N1 and T1). At the end of the experiment, mean body length of 5.4, 11.9, 11.0 and 10.01 mm and a survival rate of 79.4, 73.8, 63.5 and 30.0% were achieved. Larvae fed with algae cultured in basal medium of chcont, Dcont, Ncont and Tcont reached 9.1, 9.5, 8.0 and 8.0 mm with survival rate of 31.7, 40.4, 30.5 and 22.4% by 25 (dph), respectively. In the second trial, juvenile D. labrax (25 - 60 dph) fed with Artemia metanauplii, enriched by ch1 (the best result recommended from 1st experiment) increased their mean total length to 35.5±1.4 mm at age 60 dph. The total carbohydrate and total protein in the algae species used to enrich rotifer and Artemia significantly increased for ch1, D1, N1 and T1.Also total amino acid significantly increased at P < 0.001. The total fatty acid and total unsaturated fatty acid in the algae significantly increased (P < 0.001) for ch1, D1, N1 and T1 taking into consideration that the state of C22:6 significantly increased. The ch1 gave better growth and survival percentage followed by D1 for enrich Brachionus plicatilis and newly hatched Artemia
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