Reminiscence Effects on Inter- and Intra-Individual Differences in Pursuit Rotor Performance

Abstract

Sixty male college students were given sixty 15-sec. trials on the pursuit rotor learning task. Practice was interrupted halfway through learning by a 10-min. rest period in order to investigate whether or not a reminiscence effect would influence inter-individual differences and intra-individual variation in performance. Results were consistent with previous experimentation in that inter-individual differences increased as a result of both practice and the interpolated rest period. A corresponding effect on intra-individual variation was barely noticeable.     

Measurement Invariance of Expectancy-Value Questionnaire in Physical Education

The study was designed to determine the effect of upright-posture (UP) versus semirecumbent (SR) cycling on commonly used measures of maximal and submaximal exercise capacity. Nine healthy, untrained men (M age = 27 years, SD = 4.8 years) underwent steady-state submaximal aerobic testing followed by a ramped test to determine maximal oxygen consumption (V_O2max). Anaerobic peak and average power and total work were assessed with the Wingate test. All tests were performed in both SR and UP positions, in random order. Oxygen consumption (V_O2) and ventilation (V_E) at the maximum workrate were lower in the SR position (p < .05). At submaximal workrates (50 W and 100 W), V_O2 and V_E were equivalent in the UP and SR positions, despite differences in tidal volume and respiratory rate (p < .05). There was no difference in peak or average anaerobic power in the two positions. In summary, SR exercise was associated with a reduced V_O2max and a significantly altered ventilatory response to aerobic exercise, with no change in anaerobic power output.     

一种新颖的数字图像篡改检测方法

检测数字图像复制—粘贴型篡改是目前研究热点之一。多数复制—粘贴篡改检测方案只对刚性平移篡改具有较好的检测精度,无法有效应对更复杂的几何变换和常规信号攻击。为优化数字图像复制—粘贴篡改检测效率和精度,首次提出一种使用极坐标复指数变换（PCET）与一致性敏感哈希（CSH）的高效检测算法。首先,计算滑动窗口 PCET 系数,将其作为不变的图像局部特征|然后,根据这些特征,利用 CSH 算法快速、精确地匹配大量密集分块|最后,使用基于密集线性滤波的后处理算法消除匹配结果中的错误匹配并定位重复区域,得到最终检测结果。根据实验结果可知,该算法不仅检测精度平均提高 12.06%,而且处理时间平均缩短315.64s。因此利用对几何变换和常规信号攻击鲁棒的 PCET 系数刻画图像局部特征,并采用基于图像一致性的快速高精度匹配算法 CSH,可有效优化复制—粘贴篡改检测精度和效率。     

基于四阶累积量的CSPRIT算法

分析了基于二阶统计的CSPRIT算法在空间相关高斯噪声环境中存在的问题,提出将四阶累积量与CSPRIT算法相结合,处理一维二元相移键控信号（BPSK）和多元幅移键控信号（MASK）,实现信号到达角（DOA）的估计和波束形成器的构造。与基于二阶统计的CSPRIT算法相比,基于四阶累积量的改进算法能够有效抑制空间相关的高斯噪声,提高信号估计精度。计算机仿真验证了该算法的有效性。     

How valid are student perceptions of teaching quality across education systems?

In an international context, teaching quality is often assessed via student surveys. Yet, there is little empirical evidence for the validity of students' perceptions of teaching quality across education systems. Following an argumentative validation approach, we evaluate the reliability, stability, and international comparability of students' perceptions of teaching quality as well as their predictivity on student outcomes. Based on longitudinal data from six education systems our main findings include that student perceptions of teaching quality are 1) reliable on the class level, 2) stable between two measurements, and 3) metric invariant across education systems, yet 4) their effects on achievement, interest, and self-efficacy vary between the aspects of teaching quality and education systems. Our study provides first substantial empirical findings for the validity of student perceptions across education systems and points towards culture-specific differences in the effectiveness of teaching.