A similarity-based smoothing approach to nondimensional item analysis

The probability that an examinee chooses a particular option within an item is estimated by averaging over the responses to that item of examinees with similar response patterns for the whole test. The approach does not presume any latent variable structure or any dimensionality. But simulated and actual data analyses are presented to show that when the responses are determined by a latent ability variable, this similarity-based smoothing procedure can reveal the dimensionality of ability very satisfactorily.The author wishes to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada through grant A320, and to thank Educational Testing Service for making the data on the Advanced Placement Chemistry Exam available.     

言语产生中双词素词的语音编码

采用同音判断和音节监控方法 ,考察言语产生中双词素词语音激活的特点。选用以偏正结构的双词素词为名称的图片和与双词素词中首尾两个词素同音的两组探测字作为实验材料 ,探测字在图片呈现后 5 0毫秒 (实验一 ) ,或图片呈现前 130 0毫秒 (实验二 )出现 ,要求被试判断出现的字是否与图片名称中任何一个词素同音。实验结果与绝大部分言语产生理论的预期相反 ,对图片名称第一词素的反应慢于第二词素。考虑到首尾两个词素对整词意义贡献的差别 ,作者把实验结果解释为词素意义对语音激活的作用 :第二词素的语义重要性决定了对应音节激活的快速性 ,双词素词中词素音位激活的速度和时间性受词义和词素意义激活程度的影响 ,而不完全取决于词素发音的序列性。实验不支持音位编码从左到右、序列进行的观点     

同音字族内的听觉通道词频效应与同音字表征的激活

对于同音词家族较大的词汇(例如汉语单音节词), 听觉通道的词汇通达和词汇表征的激活会受同音词汇歧义怎样的影响, 仍不很清楚。本研究采用了两个听觉通道的实验。实验一的听写任务发现在孤立音节的同音字选择上存在歧义的同时还存在同音字族内的高频偏向, 并非随机选择; 实验二的音-字同音判断任务对比同音与不同音条件得到同音促进量, 揭示了孤立音节在激活语音表征时还会引起同音高频字表征的自动激活, 而同音低频字则受到抑制。结果说明存在同音字族内的听觉通道词频效应, 同音的高、中、低频字的表征激活具有不同等性, 导致不穷尽通达, 且同音的最高频字得到更多通达机会。这些发现难以被现有的词汇通达和同音词表征激活模型解释, 文章提出一个能够解释这些听觉通道发现的模型。     

氧化型低密度脂蛋白：致动脉粥样硬化和抗动脉粥样硬化的双重作用

研究证明,氧化型低密度脂蛋白（oxLDL）,而不是低密度脂蛋白,是致动脉粥样硬化的独立危险因素。oxLDL主要通过巨噬细胞上的清道夫受体摄入oxLDL,引起血管壁泡沫细胞的堆积和脂纹的形成;oxLDL还改变了内皮细胞、平滑肌细胞、血小板的多种功能,使之释放多种致炎细胞因子,促进了炎症细胞的趋化和聚集。但最近有报道认为,口服免疫耐量的oxLDL可弱化早期和晚期动脉粥样硬化。因此,oxLDL不仅能导致动脉粥样硬化,在某些情况下,还具有抗动脉粥样硬化的作用。本文从辩证法的角度出发,系统的阐述oxLDL的这一双重作用。     

When good theories make bad predictions

Chaos-related obstructions to predictability have been used to challenge accounts of theory validation based on the agreement between theoretical predictions and experimental data (Rueger & Sharp, 1996. The British Journal for the Philosophy of Science, 47, 93–112; Koperski, 1998. Philosophy of Science, 40, 194–212). These challenges are incomplete in two respects: (a) they do not show that chaotic regimes are unpredictable in principle (i.e., with unbounded resources) and, as a result, that there is something conceptually wrong with idealized expectations of correct predictions from acceptable theories, and (b) they do not explore whether chaos-induced predictive failures of deterministic models can be remedied by stochastic modeling. In this paper we appeal to an asymptotic analysis of state space trajectories and their numerical approximations to show that chaotic regimes are deterministically unpredictable even with unbounded resources. Additionally, we explain why stochastic models of chaotic systems, while predictively successful in some cases, are in general predictively as limited as deterministic ones. We conclude by suggesting that the way in which scientists deal with such principled obstructions to predictability calls for a more comprehensive approach to theory validation, on which experimental testing is augmented by a multifaceted mathematical analysis of theoretical models, capable of identifying chaos-related predictive failures as due to principled limitations which the world itself imposes on any less-than-omniscient epistemic access to some natural systems. We give special thanks to two anonymous reviewers for their helpful comments that have substantially contributed to the final version of this paper     

Still No Evidence For Temporally Extended Shock-frequency Reduction As A Reinforcer.

There is no consensus and very little overlap in the criticisms of my target article. Because the primary consequences of avoidance behavior are by definition alterations in the distribution of shocks in time, any theory about the reinforcement of such behavior necessarily must begin with that dimension. However, the safety‐signal version of two‐process theory calls on positively and negatively correlated stimuli, including the responses themselves serving as stimuli, to transmit the effects of those alterations to the relevant behavior. Meanwhile, the Herrnstein—Hineline single‐process theory hypothesizes an additional source of reinforcement: a direct effect of reduction in the density of shock over some extended period of time. I can find no data that selectively support that hypothesis.     

汉语音节累积词频对同音字听觉词汇表征的激活作用

汉语同音字音节的累积词频是同音单字词的具体词频之和, 即音节作为词被听到的频数, 也称为音节词频。它对词汇通达的作用还没获得一致看法。本文探讨听觉词汇通达中同音字表征的激活如何受累积词频的影响, 构成累积词频的具体词频和同音字数又会在其中起何作用。研究采用跨通道的音-字同音判断范式和配套的协方差分析分离出听觉的词汇表征激活作用。实验1固定同音字数, 同时变化累积词频和具体词频(其中具体高、低频同时也是同音字族内的高、低频), 结果发现具体词频的提高对表征激活有积极作用; 累积词频的提高仅在错误率上产生微弱的抑制作用, 而这个微弱作用可以归结为同音字族内高频字表征的激活对低频字表征的抑制。实验2固定具体词频, 同时变化累积词频和同音字数, 结果发现同音字数增加对表征激活产生抑制, 没有发现累积词频的作用。两个实验的结果说明, 音节累积词频对同音字的听觉词汇表征激活不起确定作用, 能够起作用的是同音字族内的具体词频和同音字数; 但同音字数变化的抑制作用仅在具体词频不变时才发生, 因此起决定作用的是同音字族内高频字表征激活和低频字表征抑制的机制。     

First principles study of the temperature-dependent elastic properties of W

The temperature-dependent elastic constants of body-centred cubic (bcc) phase W are presented from first principles quasi-static approach. With the quasi-harmonic approximation model, the Hugoniot equation of state and temperature-dependence linear thermal expansion coefficient is successfully obtained. The adiabatic elastic constants show a normal behaviour with temperature: decrease with increasing temperature. Based on the obtained adiabatic elastic constants, the structural stability and polycrystalline aggregate properties including bulk modulus B, shear modulus G, and B/G ratio are analysed for bcc phase W. In addition, the sound velocities as a function of temperature for bcc phase W are predicted.     

Repetition blindness and homophone blindness in young and older adults

We tested age effects on repetition blindness (RB), defined as the reduced probability of reporting a target word following presentation of the same word in a rapidly presented list. We also tested age effects on homophone blindness (HB), in which the first word is a homophone of the target word rather than a repeated word. Thirty young and 28 older adults viewed rapidly presented lists of words containing repeated, homophone, or unrepeated word pairs and reported all of the words immediately after each list. Older adults exhibited a greater degree of RB and HB than young adults using a conditional scoring method that provides certainty that blindness has occurred. The existence of RB and HB for both age groups, and increased blindness for older compared to young adults, supports predictions of a binding theory that has successfully accounted for a wide range of phenomena in cognitive aging.