Khat-chewing in liminal leisure spaces: British-Somali youth on the margins

Khat-chewing, a controversial leisure activity within the Somali diaspora in Britain, has received little attention within the academic field of Leisure Studies. This paper reports on ethnographic research to provide insights into the unique locations where young British-Somali men chew khat, exposing the liminal qualities of such localities. The paper begins with an overview of the contentious position khat-chewing occupies within Somali communities in Britain, highlighting reasons why young British-Somali men hide their association with the leisure practice. The discussion that follows considers how young male khat users conceptualise spatial environments, exposing how these locations temporarily produce a dual sense of privacy and sociality. The ambiences of such temporary leisure spaces remain open to the prospect of discovery, resulting in the use of discretionary tactics to maintain a sense of secrecy. In this context, we discuss how khat-chewing offers a sense of cultural identity and belongingness while also marking young British-Somali men as outsiders – even within their own communities.     

Non-linear Gaussian sovereign CDS pricing models

Prior literature indicates that quadratic models and the Black–Karasinski model are very promising for CDS pricing. This paper extends these models and the Black [J. Finance 1995, 50, 1371–1376] model for pricing sovereign CDS’s. For all 10 sovereigns in the sample quadratic models best fit CDS spreads in-sample, and a four factor quadratic model can account for the joint effects on CDS spreads of default risk, default loss risk and liquidity risk with no restriction to factors correlation. Liquidity risk appears to affect sovereign CDS spreads. However, quadratic models tend to over-fit some CDS maturities at the expense of other maturities, while the BK model is particularly immune from this tendency. The Black model seems preferable because its out-of-sample performance in the time series dimension is the best.     

The mechanism of credit risk contagion among internet P2P lending platforms based on a SEIR model with time-lag

The credit risk contagion of Internet peer-to-peer (P2P) lending platforms is an important part of Internet financial risk management and supervision. This study analyzes the contagion path of credit risk in Internet P2P lending. Based on complex network theory and the theory of infectious disease dynamics, the characteristics of Internet P2P lending development are combined to construct a SEIR model of credit risk transmission among Internet P2P lending platforms with time lag, and the robustness of the model is analyzed and proven. The influence of platform correlations, the susceptible immune rate, the platform elimination rate, contagion latency, the saturation coefficient, and the susceptibility input rate on credit risk contagion behavior among Internet P2P lending platforms is analyzed, using the equilibrium point and threshold value. The impact of each variable is analyzed by simulation. Corresponding countermeasures and suggestions are proposed to prevent and control credit risk contagion among these platforms.     

考虑供给与需求波动性的安全库存定量研究

本文以商业企业和MTS模式下生产企业的安全库存为研究对象,将供给与需求的变动程度作为两个动态指标研究四种不同战略与运营环境下的安全库存模型,并进一步分析了降低安全库存所需的管理杠杆.     

Incentives and Performance in Real Estate Brokerage

This article has two objectives. One is to offer a theoretical model to study how the difference in commission structures affects the performance of agents at full-commission firms (e.g., RE/MAX agents) relative to other agents. The other is to provide an empirical test of the relative performance of full-commission agents. We predict that in equilibrium the selling price and the expected time it takes to sell a listing through a full-commission agent are the same as they are with a traditional agent. Our theoretical predictions are supported by our empirical results.     

Forecast of telephonometry of Xiqing District using chaos time series

The telecommunication industry has marched into telephonometry competition age. In order to forecast telephonometry development, an effective method by using the chaos time series is proposed. And the best estimate method is presented by contrasted with mature and advanced estimate methods as follows： the stochastic forest, stochastic gradient boosting, the support vector and artificial neuron network.     

A note on the existence of unique equivalent martingale measures in a Markovian setting

Simple sufficient conditions for the existence of a unique equivalent martingale measure are provided. Furthermore, these conditions give us a handle on situations where an equivalent martingale measure cannot exist. The existence of a unique equivalent martingale measure is of relevance to problems in mathematical finance. Two examples of models for which the question of existence was unresolved are studied. By means of our results existence of a unique equivalent measure up to an explosion time is proved.     

试论生态林业系统的时空观

生态林业系统具有时间、空间两个序列的开发前景。长周期,大跨度的生态林业生产可以分解为复合的短周期方式,使生态意识与经济效益有机结合。空间组合的多层次立体开发有效地利用了光、热、水、土资源,并获得最大生物量;地域组合着眼宏观,注重研究大型骨干及网络性生态工程问题。     

Working-time reduction and employment: experiences in Europe and economic policy recommendations

The paper seeks to evaluate the evidence on the employment effectsof the collective working-time reductions in Europe over thepast 20 years. While theoretical analyses produce contradictoryassessments, most empirical studies show positive employmenteffects but take insufficient account of these conditions underwhich the reductions in working time were implemented. Theseconditions for the success of collective working-time reductionsinclude an active training policy designed to minimise skillshortages in the labour market, the modernisation of work organisation,wage increases in conjunction with productivity gains and amore equal income distribution.