An extension of Stein-Lovász theorem and some of its applications

The Stein-Lovász theorem provides an algorithmic way to deal with the existence of certain good coverings, and thus offers bounds related to some combinatorial structures. An extension of the classical Stein-Lovász theorem for multiple coverings is given, followed by some applications for finding upper bounds of the sizes of (d,s out of r;z]-disjunct matrices and (k,m,c,n;z)-selectors, respectively. This gives a unified treatment for some previously known results relating to various models of group testing.     

有限产能下单向替代的闭环供应链定价模型研究

本文分析存在产品替代策略的情况下,闭环供应链在有限产能及废旧物品回收数量有限条件下的最优定价策略,分别得出四种不同情形下的最优定价策略与利润情况。同时,分析产能限制及废旧物品回收数量限制两个条件对最优定价决策与利润水平的影响,并通过数值试验进行验证。     

Bursts and heavy tails of execution time in business processes

This paper investigates the phenomena and effects of heavy tails of execution time in business processes. We approached the heavy tails as a particular variation of business process execution, and analysed them from empirical data of its execution time. The features and possible causes of the heavy tails were investigated. A workflow simulation was conducted to simulate the heavy tails, in order to evaluate quantitatively their effects to business process performance. The simulation outcomes demonstrate that (1) even a heavy-tailed activity in a business process can cause large variation of end-to-end execution times of the process and (2) there are significant prediction gaps resulted by different assumptions of execution times between an exponential distribution and a heavy-tailed distribution.     

Socioeconomic Risk for Adolescent Cognitive Control and Emerging Risk‐Taking Behaviors

This study examined whether cognitive control mediated the association between socioeconomic status (SES; composite of income‐to‐needs ratio and parent education) and changes in risk‐taking behaviors. The sample included 167 dyads of adolescents (53% male; M_age = 14.07 years at Time 1) and their parents, assessed annually across 4 years. Parents reported socioeconomic variables at Time 1. Adolescents reported risk‐taking behaviors at Times 1 and 4, and completed a functional magnetic resonance imaging cognitive control task at Times 2 and 3. Lower SES was associated with lower behavioral (but not neural) cognitive control, which was associated with increases in risk‐taking behaviors. The findings suggest that elevated socioeconomic risk may compromise cognitive control which can cascade into maladaptive behaviors in adolescence.     

Where You Lead,I Will Follow: Exploring Sibling Similarity in Brain and Behavior During Risky Decision Making

This exploratory study examined whether social learning increases similarity in adolescent siblings’ behavior and neural patterns during risky decision making. Participants included 86 adolescents (43 sibling dyads; younger siblings: M_age = 12.2 years; 22 females; older siblings: M_age = 14.6 years; 20 females) who completed questionnaires, and a decision‐making task during an fMRI scan. Younger siblings became more similar to their older siblings’ risky decision making after observing their older sibling take risks). Younger siblings who reported greater modeling of their older sibling, and less differentiation from them, showed increased neural similarity to their older siblings in the ventromedial prefrontal cortex, and the right anterior insula and ventral striatum, respectively. These findings highlight siblings as salient social agents in how adolescents process risky decision making.     

Bayesian inference of multiple structural change models with asymmetric GARCH errors

Structural change in any time series is practically unavoidable, and thus correctly detecting breakpoints plays a pivotal role in statistical modelling. This research considers segmented autoregressive models with exogenous variables and asymmetric GARCH errors, GJR-GARCH and exponential-GARCH specifications, which utilize the leverage phenomenon to demonstrate asymmetry in response to positive and negative shocks. The proposed models incorporate skew Student-t distribution and prove the advantages of the fat-tailed skew Student-t distribution versus other distributions when structural changes appear in financial time series. We employ Bayesian Markov Chain Monte Carlo methods in order to make inferences about the locations of structural change points and model parameters and utilize deviance information criterion to determine the optimal number of breakpoints via a sequential approach. Our models can accurately detect the number and locations of structural change points in simulation studies. For real data analysis, we examine the impacts of daily gold returns and VIX on S&P 500 returns during 2007–2019. The proposed methods are able to integrate structural changes through the model parameters and to capture the variability of a financial market more efficiently.

     

Caregivers’ Mental Illness and Adolescent Delinquency Among African Americans in Chicago’s Southside: Exploring Potential Protective Factors

Child and Adolescent Social Work Journal - The aim of the present study is to identify protective factors that buffer the effect of caregiver mental illness on adolescent delinquency. Specifically,...     

缝洞型碳酸盐岩孤立溶洞注水替油实验研究

缝洞型碳酸盐岩油藏储层具有多重介质特征,储集体在空间分布上具有不连续性,油水关系复杂,流体渗流机理与砂岩油藏有本质的区别,造成油田开采难度大。注水替油是在油藏依靠自身能量无法达到自喷,并且在机抽都无法举升原油至地面的情况下,通过井口注入地层水,使得油藏能量提升,重新具有自喷能量的一种技术。针对缝洞型碳酸盐岩油气藏的注水替油开发技术还处于探索阶段,尚无普遍适用的成熟技术可以直接应用。从大量的开发实践看,对油田的动态预测和分析,应当在将油藏进一步细分为缝洞单元的基础上进行。为了研究缝洞型油藏流体流动机理及注水替油开采机理,找到一个适合缝洞型油藏合理开发的方法,针对孤立溶洞实际特征,建立物理模型,实验研究其生产动态特征,结合现场注水替油生产,从无因次产量、无因次井底流压、含水率变化曲线得出注采动态变化规律。     

郑观应女子教育观述评

郑观应是一位具有强烈爱国思想的实业家和中国早期资产阶级改良派的先驱。在他的思想体系中,女子教育思想占有重要地位。郑观应在女子教育目的观的认识上表现出从"佐子相夫"到"执业以自养"变化;在教育内容的论述上呈现出中体西用的特点;而在教育制度上则透显出强烈要求规范化的主张。     

两种语境的实践概念解读——对实践唯物主义与毛泽东《实践论》的认识

实践唯物主义是马克思所创立的新唯物主义,这一指称表明实践概念在马克思主义哲学中具有本体论意义,处于基础和核心地位。《实践论》是毛泽东运用马克思主义对中国革命实践的总结。主要探讨了实践在认识论中的作用。实践概念在实践唯物主义与《实践论》这两种语境下存在一致之处,但在范围、功能、地位上也有明显差别。理解《实践论》中的“实践”必须以实践唯物主义为基础。