中国股指期货对股票市场的流动性影响

随着中国股指期货的推出,股指期货对股票市场流动性的影响又成为一个新的课题。文章运用向量自回归(VAR)模型、Granger因果检验分析了中国股指期货对股票市场的流动性影响,检测了流动性溢价理论在中国股指期货市场的应用。最终得出结论,股票市场的买卖价差和期货现货基差之间存在双向的因果关系,即股票市场的流动性波动对投资股指期货的预期收益变化有重要的作用。     

扭带管内油的受迫对流换热实验

以30~#透平油为工质,对在光管内插入三种不同扭率扭带的受迫流动的冷、热态流阻及换热性能进行了实验。实验的雷诺数为200～1150,普朗特数为320～590,实验结果表明:在本实验范围内,插有不同扭率的全长连续扭带管的换热系数为光管的1.7～2.6倍,而阻力系数为光管的3～7.5倍;且扭率的大小对扭带的流阻与换热影响较大。另外,还对间断扭带管内油的受迫对流换热进行了实验。     

基于系统动力学的京津冀碳排放交易政策影响研究

随着经济的快速发展,环境问题日益严重,京津冀地区低碳协同发展成为关注的焦点。碳排放权交易机制作为一种市场驱动的碳减排政策,能有效地减缓气候变化,降低二氧化碳排放量。对此,本文基于系统动力学,构建京津冀碳排放交易政策仿真模型,探索不同的碳交易机制设计对京津冀地区经济和环境的影响。实证研究结果表明:(1)总体上,碳交易机制能有效地促进京津冀地区的碳减排进程,即使对经济会产生微小的负向冲击;(2)在碳交易机制设计方面,减少碳配额总量,减少免费配额发放,以及提高碳交易价格均会增大碳减排力度,并同时加剧对经济的抑制作用。     

江苏省工业碳足迹研究及情景模拟

工业碳足迹是一个复杂的动态的系统, 针对于江苏省工业碳足迹的现状, 利用系统动力学原理, 借助Vensim PLE软件, 建立了江苏省工业碳足迹系统, 把系统分为人口、资源、环境、能源4个子系统, 特别考虑到人均GDP对教育的影响, 通过教育影响技术, 最终影响CO2 排放量。通过历史数据对江苏省工业碳足迹进行仿真, 并从不同经济结构、技术条件、新能源发展情况等角度设置了4种不同的情景, 与原始情景进行比较, 对2005-2020年的工业碳足迹进行分析。从情景模拟结果可以看出:要减少江苏省工业碳足迹, 必须加大力度开发新能源, 调整能源结构, 而技术进步对于工业碳足迹的减少, 效果没有前两者显著。     

Family Characteristics and Structure as Determinants of Sexual Abuse Among Female Secondary School Students in Nigeria: A Brief Report

ABSTRACT

Child sexual abuse is associated with factors that enhance the vulnerability of the child, raising physical and mental health complications in adulthood. Three hundred and fifty students participated in this cross-sectional study. Important determinants of sexual abuse were parents not living together, not living with parents, family type, and current parents’ marital status (p < 0.05). Respondents living with both parents were two times less likely to experience sexual abuse (OR = 0.5, CI: 0.3, 0.9) than respondents living with their guardians. Respondents whose parents were living together were about two times less likely to experience sexual abuse (OR = 0.6, CI: 0.3–0.9) than respondents whose parents were not living together. Respondents whose parents were either divorced or separated were about six times more likely to experience sexual abuse (OR = 5.6, CI: 1.1–27.2) than respondents with widowed parents. The study showed that parental togetherness protected against child vulnerability and risk of being sexually abused.     

Living in displacement context: Coping strategies,changing attitudes and family dynamics among Internally Displaced Persons (IDPs) in Mindanao,Philippines

ABSTRACT

The main objective of the paper is to critically examine and document the living conditions of the Internally Displaced Persons (IDPs) from Marawi City. Forcibly displaced more than a year ago due to armed conflict, these IDPs managed to find their way to an unoccupied building in the outskirt of Iligan City, Lanao del Norte Province, Philippines. Results show their range of main concerns such as the supply of electricity and water, health services and medicines and more importantly, food. Disruptions on children’s schooling and most especially the discontinuation of their parents’ livelihood were also documented. The community is waiting for their “turn” to access better temporary shelters provided by the government. The study utilized key informant interview (KII) among 10 household heads (from among the 75 families living in the building). Their narratives reveal several coping strategies amidst insufficient government assistance and community feeling of isolation, the most glaring of those, is the dependency to social network, capitalizing on the social ties with relatives and friends for assistance. The IDPs admitted however that the same assistance is not enough. Additionally, the reduction of food consumption and selling of food relief packs remain unsustainable in coping with their destitute condition. Moreover, the article also touches on the consequence of their displacement context on socio-familial dynamics.     

高新技术产业集群对创新型城市建设的影响研究

文章将高新技术产业集群和创新型城市建设联系起来,利用系统动力学理论和工具,构建因果回路图,对高新技术产业集群作用于创新型城市建设的机制进行分析,并探索两者之间的相互联系和作用模式,以期为创新型城市的建设提供一定的参考。     

供应链管理的快速反馈营销系统与4Ps营销系统仿真

企业如何快速响应市场是企业应对外界环境变化、赢得竞争优势的关键。文章从顾客需求出发,将供应链管理与市场营销相结合,运用系统动力学的理论与方法,研究传统4Ps营销系统与基于供应链管理的快速反馈营销系统两种营销模式的运营特点与绩效。并结合X企业的实际情况,运用Vensim.PLE仿真软件对两种营销模式进行仿真模拟,比较了两种模式的运营绩效。研究表明促使顾客满意度、订单率、销售量获得长期、快速增长的关键在于改变传统的营销系统模式,建立从顾客需求出发的基于供应链管理的快速反馈营销系统。     

Counter-Examples about Lower- and Upper-Bounded Population Growth

ABSTRACT

For a unimodal growth function f having its maximum at a critical state x _c , the interval bounding the population size asymptotically is usually presented as being equal to [f ^○2(x _c ), f(x _c )]. This interval however does not represent the maximum range within which the population size can vary, even asymptotically. The actual invariant interval containing the population size is equal to: [min(x*, f ^○2(x _c )), f(x _c )], where x* denotes the non-zero fixed point, assumed to be unique, of the iteration of f.     

A probabilistic transmission and population dynamic model to assess tuberculosis infection risk

The purpose of this study was to examine tuberculosis (TB) population dynamics and to assess potential infection risk in Taiwan. A well‐established mathematical model of TB transmission built on previous models was adopted to study the potential impact of TB transmission. A probabilistic risk model was also developed to estimate site‐specific risks of developing disease soon after recent primary infection, exogenous reinfection, or through endogenous reactivation (latently infected TB) among Taiwan regions. Here, we showed that the proportion of endogenous reactivation (53–67%) was larger than that of exogenous reinfection (32–47%). Our simulations showed that as epidemic reaches a steady state, age distribution of cases would finally shift toward older age groups dominated by latently infected TB cases as a result of endogenous reactivation. A comparison of age‐weighted TB incidence data with our model simulation output with 95% credible intervals revealed that the predictions were in an apparent agreement with observed data. The median value of overall basic reproduction number (R₀) in eastern Taiwan ranged from 1.65 to 1.72, whereas northern Taiwan had the lowest R₀ estimate of 1.50. We found that total TB incidences in eastern Taiwan had 25–27% probabilities of total proportion of infected population exceeding 90%, whereas there were 36–66% probabilities having exceeded 20% of total proportion of infected population attributed to latently infected TB. We suggested that our Taiwan‐based analysis can be extended to the context of developing countries, where TB remains a substantial cause of elderly morbidity and mortality.