Squirrels in suburbia: influence of urbanisation on the occurrence and distribution of a common exotic mammal

Urbanisation is widely considered to promote the establishment of non-native species, but there is limited empirical evidence of the ecological factors driving their responses. The grey squirrel Sciurus carolinensis (Gmelin 1788) is native to North America, but is widespread in the UK and is starting to spread across Europe. It is regarded as one of the world’s worst invasive animals due to its adverse impacts on native biodiversity. We use the non-native grey squirrel population in Sheffield (UK) as a case study to assess which factors limit its distribution and abundance in urban environments. In 2010 the city-wide population of adult squirrels peaked at an estimated 6539 in autumn (0.46 squirrels/ha), with maximum local densities of 8.29/ha. These densities appear to be slightly lower than those recorded in urban environments in the species’ native range. Grey squirrels occurred more frequently at urban sites with larger amounts of green-space in the surrounding region. Local habitat characteristics were, however, more powerful predictors of urban grey squirrel occurrence and abundance than regional availability of green space. Canopy cover, seed bearing trees and supplementary feeders, provided for garden birds, positively influenced grey squirrels. The potential for grey squirrels to connect city dwellers with nature thus appears to be highest in urban locations that have considerable capacity to support native biodiversity. The beneficial impacts of supplementary feeding on grey squirrel populations is notable given concerns that squirrels can adversely influence bird populations. These habitat associations also imply that grey squirrels typically respond negatively to urbanisation, which challenges arguments that urbanisation favours exotic species.     

Student Self-Assessment as a Teaching Tool: A Pilot Study of the Sequential Criterion-Referenced Educational Evaluation System

Abstract

This report discusses the use of a student self-assessment system (Sequential Criterion-Referenced Educational Evaluation) in social work education. It reports a pilot study which examines the system's reliability and validity. The results support the utility of this repeated assessment in social work education.     

A Fair Globalization: Creating Opportunities for All∗

Much has been written recently about the supposed decline in the sovereign power of nation-states due to global economic processes and the emergence of supranational governing institutions like the World Trade Organization, the World Bank, NAFTA, the EU, etc. This has posed what some consider a problem for still largely nation-state-centric social theory in terms of making sense of what appears to be a major transformation in global governance patterns and institutions. This article argues that the apparent transformation in global governance is less historically revolutionary than evolutionary with the key being a shift in power relations among capitalist class factions at all levels of governance. Toward substantiating this claim, the article focuses on what some argue to be the (re)-emerging global political-economic significance of subnational city-regions as a result of the apparent geographic rescaling of global governance downward from dominant inter-nation-state relations. Of importance is that this apparent (re)emergence of sovereign actors at the subnational city-region scale is largely the result of this contemporary new regionalist discourse essentially rendering itself a reality. It is therefore a highly contested, and contestable, phenomenon, even in the overwhelmingly neoliberal context of the United States.

Recientemente se ha escrito mucho sobre la supuesta decadencia en el poder soberano de los estados-naciones, debido a los procesos económicos globales y el surgimiento de instituciones de gobierno supranacionales como la Organización Mundial del Comercio, el Banco Mundial, el Tratado de Libre Comercio de América del Norte, (NAFTA, por su sigla en inglés), la Unión Europea, etc. Esto ha planteado lo que algunos consideran un problema para una teoría social todavía en gran parte estado-nación-céntrica en términos de tener sentido lo que parece ser una transformación mayor en las tendencias de gobierno e instituciones globales. Este artículo sostiene que la transformación aparente en la gobernanza global es menos revolucionaria históricamente que evolutiva, siendo la clave un cambio en el poder de las relaciones entre las fracciones de la clase capitalista y todos los niveles de gobierno. Para corroborar este argumento, el artículo se enfoca en lo que algunos sostienen que es el (re)surgimiento del significado económico-político global de las regiones-ciudades subnacionales, como resultado de un aparente redimensionamiento geográfico de gobierno global descendiente de las relaciones inter-naciones-estado dominantes. Es de importancia que el (re)surgimiento de los actores soberanos en la escala de región –ciudad subnacional, se debe mayormente a este planteamiento regionalista nuevo contemporáneo, básicamente presentándose a sí mismo como una realidad. Es por eso un fenómeno altamente controvertido y discutible, incluso en el contexto abrumadoramente neoliberal de los Estados Unidos.

由于全球经济进程以及诸如世界贸易组织、世界银行、北美自贸区和欧盟等超国家治理机构的兴起而导致人们认为民族国家的主权权力受到削弱,近来已广为述及。这对在很大程度上仍以民族国家为中心的社会理论提出了一个亟需考虑的问题,如何理解全球治理模式和制度中的重大变迁。本文认为,全球治理中的显著变化与其说是历史革命性的,不如说是渐进性的,关键是各治理层次上资本家阶级各派系的权力关系的变化。为了证明这一主张,本文聚焦于一些人士所认为的（重新）兴起的次国家城市-地区的全球政治经济意义, 认为它是支配性的民族国家间关系下降为明显的全球治理地理再调整的结果。重要的是,在次国家城市-地区层次上主权行为体的明显（重新）兴起,很大程度上是当代新地区主义话语实际上使自身成为现实的结果。因此它是一个高度争论的和可争论的现象,即使是在美国压倒性的新自由主义语境下。

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Community Media Studies: An Overview

This essay provides an overview of the field of community media studies. Like the study of “alternative media,” “citizens' media,” “independent,” and “radical” media – to mention but a few of the terms applied to participatory communication projects – academic inquiry into the structures, forms, and practices of community media has surged in recent years. While scholars often use these labels interchangeably, this essay focuses on academic and practitioner perspectives that explicitly and purposefully employ the term “community media.” The overview identifies and briefly considers three prominent conceptual frameworks – media democratization, civil society, and the symbolic construction of community – which shape and inform this vibrant field of study. This overview concludes with some thoughts on the limits and possibilities of community media theory, and practice, in the new millennium.     

Modeling Endogenous Mobility in Earnings Determination

ABSTRACT

We evaluate the bias from endogenous job mobility in fixed-effects estimates of worker- and firm-specific earnings heterogeneity using longitudinally linked employer–employee data from the LEHD infrastructure file system of the U.S. Census Bureau. First, we propose two new residual diagnostic tests of the assumption that mobility is exogenous to unmodeled determinants of earnings. Both tests reject exogenous mobility. We relax exogenous mobility by modeling the matched data as an evolving bipartite graph using a Bayesian latent-type framework. Our results suggest that allowing endogenous mobility increases the variation in earnings explained by individual heterogeneity and reduces the proportion due to employer and match effects. To assess external validity, we match our estimates of the wage components to out-of-sample estimates of revenue per worker. The mobility-bias-corrected estimates attribute much more of the variation in revenue per worker to variation in match quality and worker quality than the uncorrected estimates. Supplementary materials for this article are available online.     

对中国消费者非转基因菜油支付意愿的研究

有关中国消费者关于转基因食品接受度的资料非常有限.本文则首次尝试对中国消费者关于非转基因(non-GM)食用油的支付意愿(WTP)问题进行评估.通过对北京的671个消费者进行调查采访,运用假设评价方法(contingent valuation),可推导出消费者对非转基因菜油的支付意愿.为避免调查者无响应引起的偏差,运用了双变量概率选择模式对调查数据进行分析.研究结果表明,消费者对非转基因菜油的支付意愿受到了许多因素的影响,比如价格、风险意识、受教育程度和知识水平等等.计算所得的WTP显示,平均而言,被调查者愿意支付33%的额外费用来消费非转基因菜油.这一结果表明,中国消费者对转基因油持有相当怀疑的态度.