中国A、B、H 股市间尾部相依性的趋势研究 ——基于多机制平滑转换混合Copula 模型的实证分析

尾部相依性与金融市场间的风险紧密相联系,鉴于传统研究方法存在低估或高估市场间相依性的可能,提出了多机制平滑转换混合Copula 模型,从极值风险视角出发考察了中国A、B、H 股票市场间尾部相依性的长期变化趋势,发现不同股市的尾部相依性呈现不同运动趋势,而且左右尾部相依性存在明显的非对称性和结构性变化,其非对称程度、相依性强度以及结构变化的时间、位置和速度都存在一定差异． 几次重大事件如1997 年亚洲金融危机、2001年B 股对境内开放、2002 年引入QFII、2005 年的股权分置改革、2006 年引入QDII 以及2007年的次贷危机对股市间尾部相依性产生的影响程度是不一样的．     

基于机制转换Copula模型的股市量价尾部关系研究

针对传统模型只能考察正常市场条件下的量价关系,本文构建了机制转换Copula模型来研究极端市场条件下我国股市量价间的尾部相依性,发现沪深两市收益率、绝对收益率与交易量间的尾部关系存在明显的非对称特征。高收益率、高绝对收益率对应着高交易量,而低收益率、低绝对收益率与高、低交易量不存在对应关系。另外,量价间尾部关系与机制状态有关,呈现明显的周期性动态特征与结构性变化,结构变化点对应着股市周期中较大调整的开始或结束。研究还发现沪市量价间尾部关系要强于深市,但深市收益率与交易量尾部在两机制间的变动更大,而两市绝对收益率与交易量间的尾部相依性在两机制间变动较小。     

中国股市跨行业系统性风险空间溢出关联及风险预测分析——基于尾部风险网络模型

基于条件风险价值CoVaR和SIM单指数分位数回归技术,选取2012-2018年我国股市24行业指数周频数据,构建时变的跨行业尾部风险网络,通过网络拓扑结构反映系统性风险的空间关联及潜在变化趋势。此外,引入ARDL模型探究网络结构和宏观经济变量对股市系统性风险的长短期效应,最后对系统性风险进行预测。结果表明：(1)我国股市行业板块间存在明显的系统性风险空间关联和传染效应,风险溢出网络具有“小世界”特征;(2)网络连边集中度HHI呈明显的周期性变化。在尾部事件期间,HHI指标显著增加,风险网络呈较单一的中心节点结构,网络稳定性差;(3)通过节点风险传播强度和中心化程度发现,仅通过节点内部属性判断节点的系统重要性已不够全面和准确,应结合节点在网络中的位置和关联关系来判断;信息技术、医疗保健、商业和专业服务行业是风险网络中最有影响力的行业;(4)通过ARDL-ECM模型发现网络连边集中度是系统性风险的主要影响因素,并对股市系统性风险进行了高度准确的预测。本研究可为监管机构有效识别我国股市中有影响力的行业提供参考,依据关键行业的溢出关联制定针对性的风险防范措施,同时对风险溢出效应设立预警机制。     

中美贸易摩擦对中国沪深股市行业板块的影响北大核心CSCDCSSCI

以“2018年中美贸易摩擦事件”为时间节点,分别构建贸易摩擦前、后的中国沪深股市行业间风险溢出网络.基于多种网络中心性指标,构建反映行业风险传染及风险承受强度的综合指标.从行业间风险溢出效应、股市稳定性、网络结构变化等角度分析贸易摩擦对股市的影响,探究影响各行业风险传染(承受)强度的因素,并在贸易摩擦背景下识别影响行业网络变化的主要因素.研究表明:1)贸易摩擦事件促使股市系统性风险加剧及稳定性水平下降,并降低网络的鲁棒性;2)在短期内,贸易摩擦对网络稳定性具有决定性影响.在中长期上,贸易摩擦对网络稳定性的影响逐渐减弱,而宏观经济指标、汇率、货币政策等经济政策将逐渐主导网络稳定性的变化;3)贸易摩擦后,各行业的风险溢出效应发生不同程度的改变,影响各行业风险传染(承受)强度的因素也不尽相同.研究结论对我国金融监管部门进行宏观审慎管理、把控系统性风险、维护金融市场稳定性具有一定的参考价值.     

中美贸易摩擦对中国沪深股市行业板块的影响

以"2018年中美贸易摩擦事件"为时间节点,分别构建贸易摩擦前、后的中国沪深股市行业间风险溢出网络.基于多种网络中心性指标,构建反映行业风险传染及风险承受强度的综合指标.从行业间风险溢出效应、股市稳定性、网络结构变化等角度分析贸易摩擦对股市的影响,探究影响各行业风险传染(承受)强度的因素,并在贸易摩擦背景下识别影响行业网络变化的主要因素.研究表明:1)贸易摩擦事件促使股市系统性风险加剧及稳定性水平下降,并降低网络的鲁棒性; 2)在短期内,贸易摩擦对网络稳定性具有决定性影响.在中长期上,贸易摩擦对网络稳定性的影响逐渐减弱,而宏观经济指标、汇率、货币政策等经济政策将逐渐主导网络稳定性的变化; 3)贸易摩擦后,各行业的风险溢出效应发生不同程度的改变,影响各行业风险传染(承受)强度的因素也不尽相同.研究结论对我国金融监管部门进行宏观审慎管理、把控系统性风险、维护金融市场稳定性具有一定的参考价值.     

风险相关性下的银行非预期操作风险集成度量——基于动力学模型视角

依据我国商业银行1994年~2012年操作风险历史数据,建立考虑不同时点风险单元间相关性的动力学模型来描述操作风险损失产生、传导及演化的机制.该模型指出操作风险损失产生的机制有三种:自发产生的损失、不同事件类型之间的相互影响以及银行覆盖预期损失的资本金储备.通过对损失演化模型的仿真计算,获得具有低频高损特征的非预期操作风险损失情景模拟,并计算年度总体非预期损失的VaR.实证结果表明:动力学模型能够很好地描述不同风险事件类型间不同时点的相依性结构,并通过稳健性检验;在较高置信水平下,线性叠加VaR会高估风险,高估程度会随置信水平的提升而提升;内部欺诈已成为中国商业银行操作风险最主要的风险事件类型.     

基于马尔可夫转换GARCH模型的上海股市风险研究

在本文中我们将马尔可夫转换模型与GARCH模型相结合来分析上海A股和B股市场的风险结构,实证研究发现上海A、B股市场的风险具有明显的状态转换特征,高风险状态和低风险状态在波动值和波动持续期方面存在着较大的差异,而我们的模型能够较好的捕捉到这种状态相依特征.因此马尔可夫转换GARCH模型较传统的GARCH模型能够更好地刻画上海股市的风险特征和景气状况.     

极端情况下对我国股市风险的实证研究

准确地度量风险是对风险进行有效管理的前提也是投资者做出合理的投资决策的基础,然而在极端事件频繁发生的情况下,传统的VaR计算方法难以准确地度量股市风险,极值理论却可以很好地解决这一问题。本文特别关注了由2007年美国"次贷" 危机所引发的全球金融危机爆发时我国股市的风险度量问题,考虑到全球股市间极端事件的联动效应,利用基于极值理论的POT模型对上证综指日收益率的尾部数据直接建模拟合分布,进而计算出风险值VaR和CVaR,通过比较危机前后的风险值,发现随着金融危机的到来,我国股市的风险有了一定程度的释放。     

基于动态Copula的企业集团信用风险传染效应研究

企业集团成员企业间基于业务关联、技术关联和财务关联的相互联系,构成了企业信用风险传染的重要渠道。金融机构如果缺乏对企业集团成员企业间信用风险传染的管理和防控意识,其后果可能是金融机构信贷资产遭受巨大经济损失。本文基于尾部相依性的视角构建动态协变量Joe-Clayton copula模型,实证分析企业集团成员企业信用风险传染问题。研究发现,信用风险在企业集团成员企业间存在传染效应,且这种信用风险传染效应呈现一定的动态特征;宏观经济因素和微观公司经营能力、财务状况对企业集团内部不同组别子企业间信用风险传染效应的影响从重要性程度和作用方向两个维度上存在差异。     

中国A股市场金融板块间风险相依关系及动态演化研究

将中国金融板块细分为国有大型银行、全国性股份制银行、城商行、证券、保险和信托等6个金融子板块，并以2015年中国股市异动和2019年新冠肺炎疫情为研究背景，分析在两个场景下的不同时期内，6个金融板块间的风险相依关系及其动态演化。通过计算各板块间波动指数的互信息，构建金融板块风险相依关系网络，并使用最大生成树刻画该相依关系的核心结构。研究发现，在市场处于相对平静时期，银行类金融板块与非银行类金融板块二者彼此之间的风险关联较弱，处于相对割裂状态；在市场走势波动较大时，银行类金融板块与非银行类金融板块之间的风险关联程度增强，且保险板块成为重要的中间节点；在两个场景下的异动期和疫情期，国有大型银行板块和城商行板块分别成为最大的风险节点。     

Power,authority and legitimacy

Management, human resources, organization, control, leadership, etc., all seem to be just so many euphemisms for power, and this suggests a discourse of management and organization that calls things by their proper name. This paper on the contrary stresses the need to resolve the concept of ‘power’ itself into more differentiated notions, and proposes that clarification may be derived from distinctions once explicit in the vocabulary of Classical antiquity, but lost in modern European languages. It argues that nothing but confusion in thinking about organizations, management and legitimation can result from the failure to recognize that the phenomena this vocabulary identifies and distinguishes are irreducibly different.     

Criteria for selecting a production control philosophy

Logistic objectives constitute a compromise between having short leadtimes and a low volume of work in progress on the one hand and a high resource loading and due date obligation on the other. Miscellaneous production planning approaches offered today provide different combinations of logistic objectives for satisfying a manufacturing strategy. To combine the strength of the various approaches into a unified system, a new approach based on a dynamic and distributed production planning methodology is proposed. To customize the approach, various analyses and specifications have to be made and for that reason some important characteristics and criteria for analysing production control philosophies will be given.     

The social construction of the meaning of acute stressors: a qualitative study of the personal accounts of police officers using a stress counselling service

The police profession is one in which acute stressors are encountered more frequently than in other occupations. Using the personal accounts of 35 police officers attending an in-house stress counselling clinic, the aim of the present study was to provide a qualitative examination of how the institutional context of policing influenced the ways in which acute stressors signified to individual police officers experiencing felt distress. Using the framework of Rational Emotive Behaviour Therapy as an analytical tool, it is argued that beliefs contributing to the experience of felt distress are related to the way in which policing as both an identity and an activity is constructed through the police organizational culture. Not only do these constructions influence the ways in which officers perceive themselves and their environments, but they also operate at the collective level to 'normalize' some emotional responses and to 'pathologize' others which, it is argued, could impact upon the outcomes of interventions such as stress counselling.     

The moderating role of social support in Karasek's job strain model

This paper examines whether social support is a boundary-determining criterion in the job strain model of Karasek (1979). The particular focus is the extent to which different sources of social support, work overload and task control influence job satisfaction, depersonalization and supervisor assessments of work performance. Hypotheses are tested using prospective survey data from 80 clerical staff in a university setting. Results revealed 3-way interactions among levels of support (supervisor, co-worker, non-work), perceived task control and work overload on levels of work performance and employee adjustment (self-report). After controlling for levels of negative affect in all analyses, there was evidence that high levels of supervisor support mitigated against the negative effects of high strain jobs on levels of job satisfaction and reduced reported levels of depersonalization. Moreover, high levels of non-work support and co-worker support also mitigated against the negative effects of high strain jobs on levels of work performance. The results are discussed in terms of the importance of social support networks both at, and beyond, the work context.     

Job insecurity, coping resources and personality dispositions in occupational strain

This paper presents research on the relationships between the work-related stressor of perceived job insecurity and various indicators of occupational strain, taking into account employees' personality dispositions (trait negative and positive affectivity) and coping resources. Respondents were 222 Australian public servants surveyed during organizational restructuring that involved downsizing and threat to job certainty. The research was formulated within an adaptation of Osipow, Doty, and Spokane's (1985) framework of stress-strain-coping that included the possible direct as well as moderating effects of personality dispositions in reporting occupational strain (Parkes, 1990). Findings from hierarchical regression analyses indicate consistent significant independent effects of personality dispositions, coping resources and perceived job insecurity on various indicators of strain. There was also support for the moderating roles of negative affectivity and self-care in the relation between perceived job insecurity and physical strain. Implications for the role of dispositional factors, especially negative affectivity, and the utility of various coping resources in accounting for occupational strain in times of threatened job security are discussed.     

Job stress, job strain, and psychological withdrawal among Dutch university staff: towards a dualprocess model for the effects of occupational stress

This study examined the antecedents of job strain (emotional exhaustion, health complaints) and withdrawal behaviour (e.g. lowered organizational commitment) among a cross-sectional sample of 131 academic staff members of the law department of a large Dutch university. Conservation of resources theory (Hobfoll, 1989) provided the theoretical background for this study. Strains and withdrawal behaviours were expected to be most prominent among those who reported having few resources and/or who reported high job demands. Structural equation modelling revealed that this was indeed the case. As predicted, differential patterns of effects emerged for job demands and job resources. Analysis of the effects of four job-specific stressors revealed that especially the structural aspects of a staff member's teaching task (e.g. the number of students in their classes) contributed strongly to perceived job demands. Theoretical and practical implications of the study are discussed.     

Dermal Uptake of 18 Dilute Aqueous Chemicals: In Vivo Disappearance‐Method Measures Greatly Exceed In Vitro‐Based Predictions

Average rates of total dermal uptake (K_up) from short‐term (e.g., bathing) contact with dilute aqueous organic chemicals (DAOCs) are typically estimated from steady‐state in vitro diffusion‐cell measures of chemical permeability (K_p) through skin into receptor solution. Widely used (“PCR‐vitro”) methods estimate K_up by applying diffusion theory to increase K_p predictions made by a physico‐chemical regression (PCR) model that was fit to a large set of K_p measures. Here, K_up predictions for 18 DAOCs made by three PCR‐vitro models (EPA, NIOSH, and MH) were compared to previous in vivo measures obtained by methods unlikely to underestimate K_up. A new PCR model fit to all 18 measures is accurate to within approximately threefold (r = 0.91, p < 10^?5), but the PCR‐vitro predictions (r > 0.63) all tend to underestimate the K_up measures by mean factors (UF, and p value for testing UF = 1) of 10 (EPA, p < 10^?6), 11 (NIOSH, p < 10^?8), and 6.2 (MH, p = 0.018). For all three PCR‐vitro models, log(UF) correlates negatively with molecular weight (r² = 0.31 to 0.84, p = 0.017 to < 10^?6) but not with log(vapor pressure) as an additional predictor (p > 0.05), so vapor pressure appears not to explain the significant in vivo/PCR‐vitro discrepancy. Until this discrepancy is explained, careful in vivo measures of K_up should be obtained for more chemicals, the expanded in vivo database should be compared to in vitro‐based predictions, and in vivo data should be considered in assessing aqueous dermal exposure and its uncertainty.     

Systems Resilience for Multihazard Environments: Definition,Metrics, and Valuation for Decision Making

The United Nations Office for Disaster Risk Reduction reported that the 2011 natural disasters, including the earthquake and tsunami that struck Japan, resulted in $366 billion in direct damages and 29,782 fatalities worldwide. Storms and floods accounted for up to 70% of the 302 natural disasters worldwide in 2011, with earthquakes producing the greatest number of fatalities. Average annual losses in the United States amount to about $55 billion. Enhancing community and system resilience could lead to massive savings through risk reduction and expeditious recovery. The rational management of such reduction and recovery is facilitated by an appropriate definition of resilience and associated metrics. In this article, a resilience definition is provided that meets a set of requirements with clear relationships to the metrics of the relevant abstract notions of reliability and risk. Those metrics also meet logically consistent requirements drawn from measure theory, and provide a sound basis for the development of effective decision‐making tools for multihazard environments. Improving the resiliency of a system to meet target levels requires the examination of system enhancement alternatives in economic terms, within a decision‐making framework. Relevant decision analysis methods would typically require the examination of resilience based on its valuation by society at large. The article provides methods for valuation and benefit‐cost analysis based on concepts from risk analysis and management.     

UNIX系统性能监控简述及shell系统资源统计程序

本文简要阐述了unix系统中(主要以IBM的AIX为例)进行系统性能管理的几种命令行工具,并通过编写shell实例程序,运用其中提到的工具实现系统资源利用率的统计程序,为做好unix系统管理和调优提供参考.