And yet they Co-move! Public capital and productivity in OECD

In this paper, we add to the debate on the public capital–productivity link by applying very recent developments in the panel time series literature that take into account cross sectional correlation in non-stationary panels. In particular, we evaluate the productive effect of public capital by estimating various production functions on a panel of 21 OECD countries over the period 1975–2002. Our results suggest that public capital has a positive long run impact on output, with elasticities that range between 0.05 and 0.15, depending on model specification. These findings are robust to the existence of spillover effects from public capital investments in other countries and to the inclusion of other productivity determinants, like human capital, the stock of patents and R&D capital. Finally, we do not find any important effect of public capital on GDP in the short run: this suggests that public infrastructure investments might not be a powerful countercyclical policy instrument.     

Emerging coherence and relations to communication among executive function tasks in toddlers: Evidence from a Latin American sample

Recent work within early executive function (EF) seems to suggest that toddlers show distinct patterns of development, involving poorly correlated performance across EF tasks and significant improvements over relatively short periods of time. The present study sought to extend these findings by investigating evidence for these patterns in toddlers and the existence of more traditional patterns of EF (e.g., correlations between tasks, links to language) when using the same tasks in a novel Latin American sample. Eighty toddlers (18–24 months) and sixty young preschoolers (30–36) months completed a battery of EF tasks, early social communication, and receptive and expressive language measures. Results indicated that toddlers showed similar distinct patterns of development (i.e., few relations between tasks and links to responding to joint attention), but by early preschool a more cohesive EF and links to language were present. Further, work demonstrated significant age (older children outperformed younger children), gender (girls outperformed boys), and socioeconomic differences (satisfied basic needs outperformed unsatisfied basic needs, but only on the snack delay). This work provides evidence for patterns of emerging EF development within this novel cultural sample (and evidence for group differences) that may be supported by communicative and representational development.     

中国流通A股市场投资者实现回报率研究

现实中的股票市场不可能完全符合资本市场有效性假设,因而把股票成交价格看作是股票的市场价值,并据此计算股票投资回报率的传统做法存在着明显的弊端。投资者实际实现的回报率对现实股票市场,特别是规范程度很低的我国股票市场的研究具有重要意义。本文提出了无需完全有效市场假设的现金概念及以此为基础的投资者实现回报率概念,并给出了现有条件下的投资者回报率计算公式和沪深两市的计算结果。     

A linear-time algorithm for weighted paired-domination on block graphs

Journal of Combinatorial Optimization - In a graph $$G = (V,E)$$ , a set $$S\subseteq V(G)$$ is said to be a dominating set of G if every vertex not in S is adjacent to a vertex in S. Let G[S]...     

云南边疆少数民族间的"康吧"经济交往模式:理论与实证分析

"康吧"交往是纳西族与傈僳族、藏族之间一种独特而历史悠久的物质交换模式,它不符合理性选择的逻辑却能世代延续至今,同时,不同民族间的"康吧"交往又存在差异。本文借鉴西方主流理论对这种古老的交往模式进行分析,从经济学、社会学、人类学的多重理论角度出发,采用访谈、观察与定量分析相结合的研究方法,对上述现象进行了分析。研究结果表明:(1)资源依赖性、信任和互惠原则对"康吧"交往的延续至关重要;(2)货币市场和投机行为的出现导致"康吧"交往走向衰落,但情感互惠和资源互补使之至今存在;(3)自然资源条件、资源互补程度、社会历史背景和文化因素,对交往模式的差异都有重要影响作用。     

Methodology for the Calculation of Annualized Incremental Risks in Systems of Dams

In the past few years, the field of dam safety has approached risk informed methodologies throughout the world and several methodologies and programs are appearing to aid in the systematization of the calculations. The most common way of implementing these calculations is through the use of event trees, computing event probabilities, and incremental consequences. This methodology is flexible enough for several situations, but its generalization to the case of systems of several dams is complex and its implementation in a completely general calculation methodology presents some problems. Retaining the event tree framework, a new methodology is proposed to calculate incremental risks. The main advantage of this proposed methodology is the ease with which it can be applied to systems of several dams: with a single risk model that describes the complete system and with a single calculation the incremental risks of the system can be obtained, being able to allocate the risk of each dam and of each failure mode. The article shows how both methodologies are equivalent and also applies them to a case study.     

A comparison of classification models to identify the Fragile X Syndrome

The main models of machine learning are briefly reviewed and considered for building a classifier to identify the Fragile X Syndrome (FXS). We have analyzed 172 patients potentially affected by FXS in Andalusia (Spain) and, by means of a DNA test, each member of the data set is known to belong to one of two classes: affected, not affected. The whole predictor set, formed by 40 variables, and a reduced set with only nine predictors significantly associated with the response are considered. Four alternative base classification models have been investigated: logistic regression, classification trees, multilayer perceptron and support vector machines. For both predictor sets, the best accuracy, considering both the mean and the standard deviation of the test error rate, is achieved by the support vector machines, confirming the increasing importance of this learning algorithm. Three ensemble methods - bagging, random forests and boosting - were also considered, amongst which the bagged versions of support vector machines stand out, especially when they are constructed with the reduced set of predictor variables. The analysis of the sensitivity, the specificity and the area under the ROC curve agrees with the main conclusions extracted from the accuracy results. All of these models can be fitted by free R programs.     

一种简单的过流过压保护电路

详细介绍了一种实用的过流过压保护电路及工作原理 ,该电路具有可靠性高、反应快等特点     

东海何处吊苍水─—张煌言在舟山遗迹考

本文以张煌言年谱与文集为主轴，结合实地考察，勾画出张煌言（苍水）在舟山遗迹的大概轮廓；从横向与纵向两个层面对张煌言的思想、实践和个人品质进行评价，揭示传统文化的久远影响及其意义。文章还就张煌言与郑成功以及文天祥的对比，对历史“公正”与“不公正”作了深层次的哲学思考。