Adapting the optimal job search model for active labour market policy

Summary.  The structural theoretical framework for the analysis of duration of unemployment has been the optimal job search model. Recent advances in computational techniques in Bayesian inference now facilitate the analysis of incomplete data sets and the recovery of structural model parameters. The paper uses these methods on a UK data set of the long-term unemployed to illustrate how the optimal job search model can be adapted to model the effects of an active labour market policy. Without such an adaptation our conclusion is that the simple optimal job search model may not fit empirical unemployment data and could thus lead to a misspecified econometric model and incorrect parameter estimates.     

宋濂的散文艺术与绵延意识

宋濂是由元入明的文学家,为明代文臣之首。《阅江楼记》是宋濂的名作,其结构孕育着八股文的胚基,其文气即作者强烈的历史意识。宋濂的散文艺术,上承宋人王禹傅,下启清人刘曾。宋濂不同于王、刘之处在于他那特别强烈的绵延之感。在绵延中,过去、现在和将来互相渗透浑然一体。绵延是不可量度的精神活动,而文人在此活动中快乐无比极其幸福。中华民族文化的绵延是宋濂最为关心的问题。宋濂对历史的把握是一种带有其个性特征的时间感,它从根本上决定了宋濂散文的文本品质。     

低信噪比下长码直扩信号的符号宽度估计

针对长码直扩信号,提出了一种新的符号宽度估计算法。在基于高阶自相关统计量和最大化相应的自相关系数中得到粗略估计值,然后基于伪码差分解扩的概念和二阶循环自相关函数得到精确估计值。粗略估计步骤在低信噪比和短数据长度下具有鲁棒性,给精确估计步骤提供一个可信的估计范围,从而改善了精确估计步骤的性能;在精确估计时,采用伪码差分解扩消除伪码序列对循环自相关函数的扰动。仿真表明,和现有方法相比,算法不受伪码限制,同时估计的性能有明显改善,适合于低信噪比下使用。     

我国用益物权期限“时效说”证伪

我国《物权法》规定了动产和不动产的用益物权,但只列举了一系列的不动产用益物权,并规定了部分用益物权的期限,对动产用益物权没有详细规定。有学者认为建设用地权的70年期限是除斥期间,进而推及到所有的用益物权期限是除斥期间。这一观点得到广泛的传播。然而,通过法理论证可知,现有用益物权的期限不是除斥期间,亦非取得时效或消灭时效,只是法定存续期间。     

The Emergence of Reactive Strategies in Simulated Heterogeneous Populations

The computer simulation study explores the impact of the duration of social impact on the generation and stabilization of cooperative strategies. Rather than seeding the simulations with a finite set of strategies, a continuous distribution of strategies is being defined. Members of heterogeneous populations were characterized by a pair of probabilistic reactive strategies: the probability to respond to cooperation by cooperation and the probability to respond to defection by cooperation. This generalized reactive strategy yields the standard TFT mechanism, the All-Cooperate, All-Defect and Bully strategies as special cases. Pairs of strategies interacted through a Prisoner's Dilemma game and exerted social influence on all other members. Manipulating: (i) the initial distribution of populations' strategies, and (ii) the duration of social influence, we monitored the conditions leading to the emergence and stabilization of cooperative strategies. Results show that: (1) The duration of interactions between pairs of strategies constitutes a crucial factor for the emergence and stabilization of cooperative strategies, (2) Unless sufficient learning intervals are provided, initializing the simulations with cooperative populations does not guarantee that cooperation will sustain.     

Patterns of social assistance receipt in Sweden

This article analyses the situation of Swedish-born people who became first-time receivers of social assistance in 1987 and 1992. The macroeconomic situation at the time of entry was rather different for the two cohorts and the number of new entrances increased by almost 50%. Much of the increase consisted of young adults and experience of social assistance has been shown to be fairly widespread among persons under the age of 25. Bridging the period when individuals are supported by their parents to their becoming established as wage earners has become an important function of social assistance in Sweden. The pattern of social assistance receipt is rather heterogeneous across new recipients. The complex pattern of receipt means that the duration of social assistance can appear to vary depending on one's choice of perspective. On the one hand, the median duration of social assistance receipt is as low as two years when an eleven-year follow-up period is applied. On the other hand, among people who receive social assistance during a given year, as many as half had entered receipt more than four years earlier.     

关键链项目实时滚动监控方法研究

为提高项目的按时完工率，研究了一种实时滚动的动态缓冲监控方法。新方法充分考虑了项目不确定性的变化以及各活动之间的联系，基于活动的风险暴露度对缓冲总量进行分配，并根据缓冲量的实际消耗情况，将各监控点的缓冲监控剩余量按照活动风险权重因子进行实时滚动和再分配，对用于监控的缓冲量和监控基准点进行实时动态调整。仿真实验表明，该方法可以减少错误预警的产生和因此耗费的额外成本和时间，极大地提高项目的完工概率。     

Autocontours: Dynamic Specification Testing

We propose a new battery of dynamic specification tests for the joint hypothesis of iid-ness and density function based on the fundamental properties of independent random variables with identical distributions. We introduce a device—the autocontour—whose shape is very sensitive to departures from the null in either direction, thus providing superior power. The tests are parametric with asymptotic t and chi-squared limiting distributions and standard convergence rates. They do not require a transformation of the original data or a Kolmogorov style assessment of goodness-of-fit, explicitly account for parameter uncertainty, and have superior finite sample properties. An application to autoregressive conditional duration (ACD) models for trade durations shows that the difficulty with the assumed densities lies on the probability assigned to very small durations. Supplemental materials for this article are available online.     

灰信息下关键设备生产缓冲Petri网模型研究

关键设备直接关系着产品的生产周期和质量,一定程度上可以认为是离散生产系统的"瓶颈"。因此,需要为关键设备设立一定的生产缓冲来保障其运行的持续性和平稳性。针对灰信息下的生产系统,创新性地定义灰色Petri网并设计其有效算法;在分析关键设备缓冲作用机理的基础上,针对灰信息下关键设备生产缓冲问题,构建关键设备生产缓冲的灰色Petri网模型,结合遗传算法进行仿真运算,探寻其最优解;以某产品生产线为案例,验证模型及算法的有效性和实用性,为生产系统关键设备管理工作提供了一种新的方法和思路。     

A pragmatic dose‐finding approach using short‐term surrogate efficacy outcomes to evaluate binary efficacy and toxicity outcomes in phase I cancer clinical trials

There is a growing need for study designs that can evaluate efficacy and toxicity outcomes simultaneously in phase I or phase I/II cancer clinical trials. Many dose‐finding approaches have been proposed; however, most of these approaches assume binary efficacy and toxicity outcomes, such as dose‐limiting toxicity (DLT), and objective responses. DLTs are often defined for short time periods. In contrast, objective responses are often defined for longer periods because of practical limitations on confirmation and the criteria used to define ‘confirmation’. This means that studies have to be carried out for unacceptably long periods of time. Previous studies have not proposed a satisfactory solution to this specific problem. Furthermore, this problem may be a barrier for practitioners who want to implement notable previous dose‐finding approaches. To cope with this problem, we propose an approach using unconfirmed early responses as the surrogate efficacy outcome for the confirmed outcome. Because it is reasonable to expect moderate positive correlation between the two outcomes and the method replaces the surrogate outcome with the confirmed outcome once it becomes available, the proposed approach can reduce irrelevant dose selection and accumulation of bias. Moreover, it is also expected that it can significantly shorten study duration. Using simulation studies, we demonstrate the positive utility of the proposed approach and provide three variations of it, all of which can be easily implemented with modified likelihood functions and outcome variable definitions. Copyright © 2013 John Wiley & Sons, Ltd.