Spatial variation in soil inorganic nitrogen across an arid urban ecosystem

We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO₃-N and NH₄-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO₃-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH₄-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO₃-N and NH₄-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO₃-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.     

A social identity model of prosocial behaviors within nonprofit organizations

This study draws on social identity theory, while developing and testing the Social Identification Model of Prosocial Behavior among voluntary participants in nonprofit organizations. This model posits relationships between organization identification, commitment, satisfaction, and prosocial behavior among nonprofit volunteers. Path analysis results indicate successful identification of the model. Specifically, when volunteers identified with their nonprofit, they had higher levels of prosocial behaviors, commitment, and satisfaction. This study provides several important extensions to social identity theory and nonprofit literatures while highlighting the need for further research examining motivations behind prosocial behaviors within nonprofits.     

区域民族描写民俗学优秀之作--读《中国南楚民俗学》

从民俗理论的实际提炼性与追求规范性、区域民族民俗描写研究之丰富性与精确性、田野考察之可学性与可操作性、民俗学研究之献身性与交心工程性四个方面来考察 ,王建章教授的《中国南楚民俗学》是区域民族描写民俗学的优秀著作。     

对建构主义教学观的几点认识

围绕建构主义教学观与传统教学观、建构主义教学策略、建构主义教学模式等几个方面 ,就数学教学谈了对建构主义教学观的几点认识     

LOG-PERIODOGRAM ESTIMATION OF LONG MEMORY VOLATILITY DEPENDENCIES WITH CONDITIONALLY HEAVY TAILED RETURNS

Many recent papers have used semiparametric methods, especially the log-periodogram regression, to detect and estimate long memory in the volatility of asset returns. In these papers, the volatility is proxied by measures such as squared, log-squared, and absolute returns. While the evidence for the existence of long memory is strong using any of these measures, the actual long memory parameter estimates can be sensitive to which measure is used. In Monte-Carlo simulations, I find that if the data is conditionally leptokurtic, the log-periodogram regression estimator using squared returns has a large downward bias, which is avoided by using other volatility measures. In United States stock return data, I find that squared returns give much lower estimates of the long memory parameter than the alternative volatility measures, which is consistent with the simulation results. I conclude that researchers should avoid using the squared returns in the semiparametric estimation of long memory volatility dependencies.     

格里耶的写物理论

站在现代非人类中心主义的立场上 ,法国新小说理论家罗伯 -格里耶认为物我关系是一种距离关系 ,两者既不同性质 ,也无相辅相成的内在联系。因此 ,他反对巴尔扎克以人化的方式写物。他主张 :1、站在物件之外写物 ;2、描写事物的平面 ;3、记录物我距离而非物我分离 ;4、摈弃人化的语言 ,引入几何学的描写。写物理论是格里耶失误最多的理论之一 ,也是极具原创性、开放性和影响力的理论之一     

英汉广告常用辞格及其功能

广告修辞新奇巧妙 ,独出心裁 ,凝聚了广告作者的丰富而非凡的想像力 ;广告语篇中恰当而巧妙地运用修辞格不但使广告语言生动活泼 ,言简意赅 ,或节奏感强 ,很有力量 ,而且深刻地描绘或强调广告商品或服务的特征、特性与功能 ,有助于创造其美好形象 ,促进广告走向成功。     

中学生课业负担过重的原因与对策

中学生课业负担过重 ,有其现实的社会物质根源和传统意识根源 ,有学校内部因素和社会环境因素的相互影响。减轻学生课业负担 ,需要加大教育投入 ,转变教育观念 ,创新评估机制 ,提高教师的职业道德素质和业务水平。     

Bayesian modelling of catch in a north-west Atlantic fishery

Summary. We model daily catches of fishing boats in the Grand Bank fishing grounds. We use data on catches per species for a number of vessels collected by the European Union in the context of the Northwest Atlantic Fisheries Organization. Many variables can be thought to influence the amount caught: a number of ship characteristics (such as the size of the ship, the fishing technique used and the mesh size of the nets) are obvious candidates, but one can also consider the season or the actual location of the catch. Our database leads to 28 possible regressors (arising from six continuous variables and four categorical variables, whose 22 levels are treated separately), resulting in a set of 177 million possible linear regression models for the log-catch. Zero observations are modelled separately through a probit model. Inference is based on Bayesian model averaging, using a Markov chain Monte Carlo approach. Particular attention is paid to the prediction of catches for single and aggregated ships.