教育均衡与教育发展之间的悖论——对教育均衡问题的一种解读

教育发展与教育均衡之间存在着悖论:随着我国教育的改革与发展,教育的规模、投入与数量持续扩张,但教育均衡程度与水平却在下降,甚至出现一定程度的恶化。这不仅是理论与逻辑上的推论,也是为我国教育实践所证明了的事实。产生此悖论的原因在于,在我国教育发展的当前阶段,由于参考群体的变化,人们产生了普遍的相对剥夺感,教育均衡或公平感走低,从而引致整个社会对教育不均衡现象的广泛批评。教育发展与教育均衡之间也呈现出经济学上的倒U型曲线关系,这从另一个侧面证明了教育发展与教育均衡之间悖论存在的合理性。     

动态总需求-总供给模型的介评

DAD-DAS模型是由美国经济学家曼昆提出来的,它反映的是通货膨胀与产量缺口之间的联系。该模型含有预期、货币政策规则、产量缺口、通货膨胀目标和随机冲击等因素,说明的经济波动方式和机理与传统的AD-AS模型不同。货币政策在短期内有效,长期无效,古典二分法成立,并且存在着产量易变性和通货膨胀易变性的交替。中央银行在实施货币政策时,必须按照泰勒原则抉择才能更好地稳定通货膨胀。本文首先对模型作了简要的介绍,然后重点对其优点和缺点进行了评价。     

平面Bézier曲线细分算法的参数优化

复杂曲线逼近是CAGD中的基本问题,传统deCasteljau算法通常固定细分参数为0.5.本文考虑平面Bézier曲线的凸包最小和扁平度最小两种情况,分别给出凸包最优和扁平度最优的细分参数的定义和计算方法,使每次细分后得到的新控制多边形更好地逼近原曲线.通过分析不同类型曲线的最优参数发现,对于较小的曲线段,细分参数选为0.5具有一定的合理性.比较扁平最小方法与deCasteljau定参数方法发现:对于形状复杂的曲线,前者细分效率提高50%以上;对于简单曲线,二者相当.     

基于曲线匹配的星载激光测高仪无场在轨几何定标方法

星载激光测高技术的快速发展急需有效的在轨几何定标方法来校正测高数据中的系统误差。探索一种基于曲线匹配的测高仪无场在轨几何定标方法。该方法利用激光足印高程曲线与DEM进行匹配获得激光足印控制点进而实现定标参数求解,无需到野外布设探测器定标场地。采用资源三号02星激光测高数据进行定标方法验证,并对定标结果进行精度评估。实验表明,经本文的定标方法校正后的测高数据的精度得到显著提升,验证了本方法的有效性。     

Responses to oral glucose challenge differ by physical activity volume and intensity: A pilot study

BackgroundOne-hour postprandial hyperglycemia is associated with increased risk of type 2 diabetes and cardiovascular disease. Physical activity (PA) has short-term beneficial effects on post-meal glucose response. This study compared the oral glucose tolerance test results of 3 groups of people with habitually different levels of PA.MethodsThirty-one adults without diabetes (age 25.9 ± 6.6 years; body mass index 23.8 ± 3.8 kg/m²; mean ± SD) were recruited and divided into 3 groups based on self-reported PA volume and intensity: low activity < 30 min/day of moderate-intensity activity (n = 11), moderately active ≥ 30 min/day of moderate-intensity PA (n = 10), and very active ≥ 60 min/day of PA at high intensity (n = 10). Participants completed an oral glucose tolerance test (50 g glucose) with capillary blood samples obtained at baseline, 15 min, 30 min, 45 min, 60 min, 90 min, and 120 min post-ingestion.ResultsThere were no significant differences between groups for age or body fat percentage or glycated hemoglobin (p > 0.05). The groups were significantly different in terms of baseline glucose level (p = 0.003) and, marginally, for gender (p = 0.053) and BMI (p = 0.050). There was a statistically significant effect of PA on the 1-h postprandial glucose results (p = 0.029), with differences between very active and low activity groups (p = 0.008) but not between the moderately active and low activity groups (p = 0.360), even when baseline glucose level and gender differences were accounted for. For incremental area under the curve there was no significant effect of activity group once gender and body fat percentage had been accounted for (p = 0.401). Those in the low activity group took 15 min longer to reach peak glucose level than those in the very active group (p = 0.012).ConclusionThe results suggest that high levels of PA have a beneficial effect on postprandial blood glucose profiles when compared to low and moderate levels of activity.     

转型升级中的学会学习:好孩子公司案例研究

本文首先对传统上本土企业"知识溢出"的思想进行质疑,认为代工企业存在学习失效。本文通过好孩子公司沿全球价值链攀升的案例,认为代工企业转型升级需要组织学习模式的转化:从学习方向上来说成功地从外驱式学习转化为内省式学习、从学习方式上来说从单一的探索式或利用式学习转化为两者均衡的双元学习。此过程中公司创业是制度保证。本文最后还强调了技术创新与管理创新的同步性,并对有些代工企业不成功的原因进行了解读。     

用ABC曲线法评价湛江红树林自然保护区的环境状况

通过2005年4月（枯水期）和7月（丰水期）对湛江红树林自然保护区高桥镇核心区大型底栖动物的调查，以丰度生物量比较（ABC曲线）法评价湛江红树林自然保护区的环境状况，结果表明，德耀村红树林剖面在4月份受轻度污染，7月份受中度污染；而红寨村红树林剖面4月和7月份均受到严重污染．     

Fitting Unstructured Finite Mixture Models in Longitudinal Design: A Recommendation for Model Selection and Estimation of the Number of Classes

In longitudinal design, investigating interindividual differences of intraindividual changes enables researchers to better understand the potential variety of development and growth. Although latent growth curve mixture models have been widely used, unstructured finite mixture models (uFMMs) are also useful as a preliminary tool and are expected to be more robust in identifying classes under the influence of possible model misspecifications, which are very common in actual practice. In this study, large-scale simulations were performed in which various normal uFMMs and nonnormal uFMMs were fit to evaluate their utility and the performance of each model selection procedure for estimating the number of classes in longitudinal designs. Results show that normal uFMMs assuming invariance of variance–covariance structures among classes perform better on average. Among model selection procedures, the Calinski–Harabasz statistic, which has a nonparametric nature, performed better on average than information criteria, including the Bayesian information criterion.     

Considerations for the use of functional principal components analysis in sports biomechanics: examples from on-water rowing

The proliferation of new biomechanical technology in laboratory and field settings facilitates the capture of data-sets consisting of complex time-series. An understanding of the appropriate statistical approaches for analysing and interpreting these data-sets is required and the functional data analysis (FDA) family of statistical techniques has emerged in the biomechanical literature. Given the use of FDA is currently in its infancy with biomechanical data, this paper will form the first of a two part series aiming to address practical issues surrounding the application of FDA techniques in biomechanics. This work focuses on functional principal components analysis (fPCA), which is explored using existing literature and sample data from an on-water rowing database. In particular methodological considerations for the implementation of fPCA such as temporal normalisation of data, removal of unwanted forms of variation in a data-set and documented methods for preserving the original temporal properties within a set of curves are explored in detail as a part of this review. Limitations and strengths of the technique are outlined and recommendations are provided to encourage the appropriate use of fPCA within the field of applied sports biomechanics.     

正确运用洛伦茨曲线和基尼系数调节收入分配

洛伦茨曲线和基尼系数作为一种统计方法,已被广泛应用于经济社会发展的各个领域。本文重点介绍洛伦茨曲线和基尼系数的含义,图形绘制与系数的运算方法,并对如何正确运用其分析结果进行了简要的论述。