Effect of target-masker similarity on across-ear interference in a dichotic cocktail-party listening task

Similarity between the target and masking voices is known to have a strong influence on performance in monaural and binaural selective attention tasks, but little is known about the role it might play in dichotic listening tasks with a target signal and one masking voice in the one ear and a second independent masking voice in the opposite ear. This experiment examined performance in a dichotic listening task with a target talker in one ear and same-talker, same-sex, or different-sex maskers in both the target and the unattended ears. The results indicate that listeners were most susceptible to across-ear interference with a different-sex within-ear masker and least susceptible with a same-talker within-ear masker, suggesting that the amount of across-ear interference cannot be predicted from the difficulty of selectively attending to the within-ear masking voice. The results also show that the amount of across-ear interference consistently increases when the across-ear masking voice is more similar to the target speech than the within-ear masking voice is, but that no corresponding decline in across-ear interference occurs when the across-ear voice is less similar to the target than the within-ear voice. These results are consistent with an "integrated strategy" model of speech perception where the listener chooses a segregation strategy based on the characteristics of the masker present in the target ear and the amount of across-ear interference is determined by the extent to which this strategy can also effectively be used to suppress the masker in the unattended ear.     

Interference from audio distracters during speechreading

Although many audio-visual speech experiments have focused on situations where the presence of an incongruent visual speech signal influences the perceived utterance heard by an observer, there are also documented examples of a related effect in which the presence of an incongruent audio speech signal influences the perceived utterance seen by an observer. This study examined the effects that different distracting audio signals had on performance in a color and number keyword speechreading task. When the distracting sound was noise, time-reversed speech, or continuous speech, it had no effect on speechreading. However, when the distracting audio signal consisted of speech that started at the same time as the visual stimulus, speechreading performance was substantially degraded. This degradation did not depend on the semantic similarity between the target and masker speech, but it was substantially reduced when the onset of the audio speech was shifted relative to that of the visual stimulus. Overall, these results suggest that visual speech perception is impaired by the presence of a simultaneous mismatched audio speech signal, but that other types of audio distracters have little effect on speechreading performance.     

Phase Transitions in a Highly Anisotropic Antiferromagnetic Heisenberg Toda Chain

The behavior of the antiferromagnetic spin 112 Heisenberg Toda chain is investigated in a space of interactions which include exchange anisotropy, bond alternation and Toda-like spinlattice coupling by means of coherent-state for spin. We analyse magnetically driven lattice instabilities and find that multiphase structure only occurs under the condition, of bond alternation. Three phase diagrams and tricritical points are obtained and some relevant physical properties are discussed.     

邻羟基萘甲醛缩对二甲氨基苯甲酰腙的合成及其对锌离子的识别

设计并合成了用于识别锌离子的荧光传感分子——2-羟基-1-萘甲醛缩-4-二甲氨基苯甲酰腙(1),其结构经1H NMR,IR和MS表征。利用荧光光谱研究了在乙腈中1对过渡金属离子(Zn2+,Cd2+,Cu2+,Hg2+,Pb2+和N i2+)的识别能力。结果表明:1表现出对Zn2+的良好选择性,Zn2+的加入导致1的长波长荧光增强449倍。Job曲线确定1与Zn2+形成1∶1型配合物。     

Reflection and transmission characteristics of ultrasonic guided waves in fractured long bone

Assessment of fractured long bone using ultrasonic guided wave（GW） has gained considerable attention.This paper focuses on using the hybrid boundary element method （HBEM） to analyze the propagation characteristics of ultrasonic GW in fractured long bones. The reflection coefficients（RC） and transmission coefficients（TC） for different depth-to-width ratio（d/w） cracks were numerically calculated and analyzed.It has been shown that the primary output modes,which include the transmission and reflection modes,are the same as the incidence modes.For some cracks,different TC curves always got the local maxima in adjacent frequencies.For different d/w cracks,most of the TC curves had local maxima which are not overlapped.These simulation results are helpful to optimize the modes and frequencies of the incidence GWs for quantitatively evaluating the bone quality and providing the numeral results of the cracks in long cortical bones.     

骨小梁中超声背散射信号的频率分析及其微结构的估计

骨质疏松症是一种骨强度下降的全身性骨骼疾病,骨强度的下降是骨量减少和骨微结构退化的共同结果。相比于传统的超声透射方法,超声背散射法可提供更多的骨微结构信息,而对于松质骨结构的建模能有助于结构信息的获取。本文将骨小梁简化为单圆柱模型(圆柱状的单根骨小梁浸于骨髓中),并基于此模型对超声背散射与频率的关系进行分析。用铝线代替骨小梁做仿体实验,通过实验与理论结果的比较来验证单圆柱模型的可行性。     

超声轴向传播技术评价长骨的研究

用超声轴向传播技术评价长骨状况已成为近年来的一个研究热点。本文首先介绍了第一到达波(FAS)法、超声Lamb波及柱面导波法在评价长骨皮质骨状况方面的研究进展,最后分析和讨论了当前研究中存在的问题及应该研究的方向。     

Joint spectrogram segmentation and ridge-extraction method for separating multimodal guided waves in long bones

Ultrasonic guided waves (GWs) can be used to evaluate long bones effectively because of the ability to provide the information of the whole bone. In this study, a joint spectrogram segmentation and ridge-extraction (JSSRE) method was proposed to separate multiple modes in long bones. First, the Gabor time-frequency transform was applied to obtain the spectrogram of multimodal signals. Then, a multi-class image segmentation algorithm was used to find the corresponding region of each mode in the spectrogram, including an improved watershed transform and a region growing procedure. Finally, the ridges were extracted and the time domain signals representing individual modes were reconstructed from these ridges in each region. The validations of this method were discussed by simulated multimodal signals with different signal-to-noise ratios (SNR). The correlation coefficients between the original signals without noise and the reconstructed signals were calculated to analyze the results quantitatively. The results showed that the extracted ridges were in good agreement with generated theoretical dispersion curves, and the reconstructed signals were highly related to the original signals, even under the SNR=3 dB situation.     

Cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase

ABSTRACT

The synthesis and characterisation of several members of the 1,ω-bis(4-cyanobiphenyl-4′-yl) alkane (CBnCB) and the 1-(4-cyanobiphenyl-4′-yloxy)-ω-(4-cyanobiphenyl-4′-yl) alkane (CBnOCB) homologous series are reported. The new odd members described CB5CB, CB13CB, CB4OCB, CB8OCB and CB10OCB all exhibit twist-bend nematic and nematic phases. The members of these series already reported in literature, CB7CB, CB9CB, CB11CB and CB6OCB, were also prepared in order to allow for a direct comparison of their transitional properties. The properties of these dimers are also compared to those of the corresponding members of the 1,ω-bis(4-cyanobiphenyl-4,-yloxy) alkanes (CBOnOCB). For any given total spacer length, for odd members of these series, the nematic–isotropic transition temperatures and associated entropy changes are greatest for the CBOnOCB dimer and lowest for the CBnCB dimer. These trends are understood in terms of molecular shape. For short spacer lengths, the twist-bend nematic–nematic transition temperature (T_NTBN) is higher for the CBnOCB series than for the CBnCB series but this is reversed as the spacer length increases. Of the CBOnOCB dimers, a virtual value of T_NTBN was estimated for CBO3OCB and T_NTBN was measured for CBO5OCB. These values are considerably lower than those observed for the corresponding members of the CBnCB or CBnOCB series. The dependence of T_NTBN on molecular structure is discussed not only in terms of the molecular curvature but also in the ability of the molecules to pack efficiently. As the temperature range of the preceding nematic phase increases, so the twist-bend nematic–nematic transition entropy change decreases and the transition approaches second order for the longer spacers. For comparative purposes, the transitional behaviour of the even-membered dimers CB6CB, CB5OCB and CBO4OCB is reported and differences accounted for in terms of molecular shape.