Across-shore distribution of Ocypode quadrata burrows in relation to beach features and human disturbance

Spatial distribution patterns of the ghost crab Ocypode quadrata were analysed using different approaches at one disturbed and two preserved reflective sandy beaches of the Mexican Caribbean. We used spatial correlation analysis to describe the across-shore distribution of O. quadrata and their patch dynamics by beach and sampling time. In addition, we analysed the across-shore variability of habitat extent of O. quadrata (habitat envelope) and its relation to human disturbance and beach features. The spatial structure of burrow density was consistent through time, showing a bimodal distribution with very low abundance in the mid distribution range and a discrete increment of burrows to landward. Nonetheless, the size of patches varied temporally for the three beaches. Burrow size increased from seaward to landward. The location of the first burrow and the habitat envelope varied among sampling times and beaches. The location of the first burrow is mostly mediated by the swash climate, while the habitat envelope is mainly controlled by the level of human disturbance. Despite the low number of disturbed and control beaches, our results suggest that the habitat envelope could be included in future studies when using ghost crabs as indicators of human disturbance. Polynomial models and variographic analysis proved to be useful tools to describe the across-shore distribution and patch dynamics of the ghost crab.     

Voluntarism and Citizenship: A Response to Lena Dominelli

This article responds to Dominelli’s contribution by mapping three lines of discussion. The first relates to the issue of how to understand voluntary work with regard to the realization of citizenship. The authors argue that this understanding depends on the way citizenship is conceived. Whereas a rights-based conception of citizenship focuses on issues of equal access to voluntary work, a duty-oriented notion of citizenship tends to see voluntarism as embedded in an educational strategy, alongside professionalized social work. The authors plead for an alternative understanding of voluntary work and social work as joined partners in practices of ‘learning democracy’. The second line of discussion revolves around the relation between social and political dimensions of citizenship. With Dominelli, the authors point out how the obscuring of the political dimension risks to nurture societal discourses that put pressure on the welfare state. The third point relates to the difficulties in positioning voluntary work with regard to professional social work. One of these difficulties is the tendency to over-romanticize voluntary work as warm, informal, generous, while giving an exclusively technical reading of social work professionalization.     

Why Do Students Leave Education Early? Theory and Evidence on High School Dropout Rates

This paper contributes to the growing literature on school dropout by proposing and empirically testing a theoretical framework on the enrollment decision of youngsters in secondary education. The model relates school dropout to time preferences, motivation, opportunity costs and policy measures. It is empirically tested on longitudinal data of about 4000 Dutch vocational students. We evaluate the enrollment decision of students for (i) different intensity levels of dropout prevention policy, and for (ii) different levels of economic development. The results indicate that the model can accurately predict actual enrollment rates over the period 2000–2013. Copyright © 2016 John Wiley & Sons, Ltd.     

一种基于分层法的区间数多属性决策方法及应用

针对以区间数形式给出属性值、未知属性权重、较多待选方案的多属性决策问题,借鉴水桶理论和现代企业投票制度,将分层法与超立方体分割相结合,给出了一种新决策方法. 新方法的优点是能够充分利用不确定信息. 最后,我们给出了一个实际应用的例子验证新方法的有效性.     

克鲁兹王莲的露地栽培及引种研究

通过对克鲁兹王莲引进及引种地自然条件的比较及物侯期、发芽情况、开花情况的调查，结果表明，克鲁兹王莲在郑州地区通过前期温室催芽，一年生露地栽培，种子水藏越冬，就可达到自繁自育的目的，把克鲁兹王莲一年生栽培的理论北限线向北推移了７００公里。     

Polycystins and cellular Ca2+ signaling

The cystic phenotype in autosomal dominant polycystic kidney disease is characterized by a profound dysfunction of many cellular signaling patterns, ultimately leading to an increase in both cell proliferation and apoptotic cell death. Disturbance of normal cellular Ca²⁺ signaling seems to be a primary event and is clearly involved in many pathways that may lead to both types of cellular responses. In this review, we summarize the current knowledge about the molecular and functional interactions between polycystins and multiple components of the cellular Ca²⁺-signaling machinery. In addition, we discuss the relevant downstream responses of the changed Ca²⁺ signaling that ultimately lead to increased proliferation and increased apoptosis as observed in many cystic cell types.     

SX360型自卸车车架动静态特性分析

建立了以板单元为基本单元的车架有限元分析模型,利用有限元分析软件ALGORFFAS对其进行了静态、自由振动和随机振动分析。将计算结果与实验数据进行对比,验证了计算的正确性,找出了车架裂纹过早出现的原因,得出了有限元分析结果,实验结果与使用中出现的车架异常断裂情况相吻合的结论,最后给出了对该种车架结构改造的方法。