Research on e-commerce transaction networks using multi-agent modelling and open application programming interface

We provide a formal definition of an e-commerce transaction network. Agent-based modelling is used to simulate e-commerce transaction networks. For real-world analysis, we studied the open application programming interfaces (APIs) from eBay and Taobao e-commerce websites and captured real transaction data. Pajek is used to visualise the agent relationships in the transaction network. We derived one-mode networks from the transaction network and analysed them using degree and betweenness centrality. Integrating multi-agent modelling, open APIs and social network analysis, we propose a new way to study large-scale e-commerce systems.     

The asymmetric relationship between returns and implied volatility: Evidence from global stock markets

We investigate the asymmetric relationship between returns and implied volatility for 20 developed and emerging international markets. In particular we examine how the sign and size of return innovations affect the expectations of daily changes in volatility. Our empirical findings indicate that the conditional contemporaneous return-volatility relationship varies not only based on the sign of the expected returns but also upon their magnitude, according to recent results from the behavioral finance literature. We find evidence of an asymmetric and reverse return-volatility relationship in many advanced, Asian, Latin-American, European and South African markets. We show that the US market displays the highest reaction to price falls, Asian markets present the lowest sensitivity to volatility expectations, while the Euro area is characterized by a homogeneous response both in terms of direction and impact. These results may be safely attributed to cultural and societal characteristics. An extensive quantile regression analysis demonstrates that the detected asymmetric pattern varies particularly across the extreme distribution tails i.e., in the highest/lowest quantile ranges. Indeed, the classical feedback and leverage hypotheses appear not plausible, whilst behavioral theories emerge as the new paradigm in real-world applications.     

Cost-effectiveness of a continuous glucose monitoring system with trending and rate information to predict hypoglycaemia and hyperglycaemia in pregnant women with insulin-dependent diabetes mellitus

Summary

This study seeks to determine the cost-effectiveness of the FreeStyle Navigator? continuous glucose monitoring system compared with self-monitoring of blood glucose (SMBG) when predicting hypoglycaemia and hyperglycaemia in pregnant women with insulin-dependent diabetes mellitus. A Markov model was constructed, and initial model analysis demonstrates that use of the FreeStyle Navigator? by a patient who is trained in diabetes management is more cost-effective than SMBG, resulting in an incremental cost-effectiveness ratio of $267 per quality-adjusted life-month ($3,204 per quality-adjusted life-year). The real-time glucose level rate of change and trend information provided by the FreeStyle Navigator? allows appropriately trained patients to improve upon decisions regarding self-treatment to prevent hypoglycaemic and hyperglycaemic episodes, resulting in a lower treatment cost and higher effectiveness than untrained patients. Based on current performance attributes, a device such as the FreeStyle Navigator? would be more cost-effective than other glucose-monitoring devices, meeting the $50,000/QALY willingness-to-pay threshold used by payers for adoption of new technology.     

Computer Simulation as a Tool for Planning and Management of Visitor Use in Protected Natural Areas

The United Nations Environment Programme’s Principles on Implementation of Sustainable Tourism suggest that implementing sustainable tourism must include monitoring visitor use of protected natural areas and directing it to areas where the environmental and social impacts of tourism are minimised. Thus, sustainable tourism management requires information about the spatial and temporal flow of visitor use in protected natural areas to help identify potential tourism-related threats to the natural and cultural resources of an area and the quality of visitors’ experiences. Recent research has identified at least four ways in which simulation modelling of visitor use can facilitate more informed planning and management of sustainable tourism in protected natural areas, including (1) describing existing visitor use flows; (2) monitoring the condition of ‘hard to measure’ indicator variables; (3) testing the effectiveness of alternative visitor use management practices; and (4) guiding the design of research on public attitudes. The purpose of this paper is to demonstrate, using findings from studies conducted in the Inyo National Forest and Isle Royale National Park, USA, each of these four potential contributions of computer simulation to sustainable tourism management and planning. The paper concludes with an assessment of the limitations of existing applications of computer simulation to nature-based tourism and recommendations for future research.     

A support methodology for EAI and BPM projects in SMEs

This paper presents a support methodology that facilitates the analysis of shared information between applications. The contemporary needs of information systems within companies rely on the integration of different applications. As a consequence, integration projects called EAI (enterprise application integration) and BPM (business process management) have arisen. These projects need support methodologies to facilitate the process of information integration. The aforementioned methodology also helps companies to align management applications with their business processes and to define the integration of the company's information systems.     

Can banks default overnight? Modelling endogenous contagion on the O/N interbank market

We propose a new model of the liquidity-driven banking system focusing on overnight interbank loans. This significant branch of the interbank market is commonly neglected in the banking system modelling and systemic risk analysis. We construct a model where banks are allowed to use both the interbank and the securities markets to manage their liquidity demand and supply as driven by prudential requirements in a volatile environment. The network of interbank loans is dynamic and simulated every day. We show how the intrasystem cash fluctuations alone, without any external shocks, may lead to systemic defaults, and what may be a symptom of the self-organized criticality of the system. We also analyze the impact of different prudential regulations and market conditions on the interbank market resilience. We confirm that the central bank’s asset purchase programmes, limiting the declines in government bond prices, can successfully stabilize banks’ liquidity demands. The model can be used to analyze the interbank market impact of macroprudential tools.     

A new economics approach to modelling policies to achieve global 2020 targets for climate stabilisation

This paper explores a Post Keynesian, ‘new economics’ approach to climate policy, assessing the opportunities for investment in accelerated decarbonisation of the global economy to 2020 following the Great Recession of 2008–2009. The risks associated with business-as-usual growth in greenhouse gas (GHG) concentrations in the atmosphere suggest that avoiding dangerous climate change will require that the world’s energy-economy system is transformed through switching to low-carbon technologies and lifestyles. Governments have agreed a target to hold the increase in temperatures above pre-industrial levels to at most 2°C and have offered reductions by 2020 in GHG emissions or the carbon-intensity of GDP. The effects of policies proposed to achieve pathways to 2020 towards this target are assessed using E3MG, an Energy-Environment-Economy (E3) Model at the Global level. E3MG is an annual simulation econometric model, estimated for 20 world regions over 1972–2006 adopting a new economics approach. Additional low-GHG investment of some 0.7% of GDP, with carbon pricing and other policies, is sufficient to achieve a pathway consistent with a medium chance of achieving the long-term target. GDP is above reference levels because decarbonisation reduces world oil prices and increases investment. Employment is some 0.9% above reference levels by 2020 and public finances are almost unaffected.     

Measuring the impact of the approach to migration in the quality of web service interfaces

There is a good consensus on the strategic value of service-oriented architecture (SOA) as a way of structuring systems, and a common trend is to migrate legacy applications that use outdated technologies and architectures to SOA. We study the effects in the resulting Web Service interfaces of applying two traditional migration approaches combined with common ways of building services, namely, direct migration with code-first and indirect migration with contract-first. The migrated system was a 35-year-old COBOL system of a government agency that serves several millions of users. In addition, we provide a deep explanation of the trade-offs involved in following either combinations. Results confirm that the ‘fast and cheap’ approach to move into SOA, which is commonplace in the industry, may deliver poor service interfaces, and interface quality is also subject to the tools supporting the migration process.     

泡沫时期中国权证产品收益率的可预测性研究

本文运用Black-Scholes公式计算权证的理论价格并和权证实际价格比较,发现权证的实际价格严重偏离理论价格,权证产品处于泡沫时期。通过Campbell和Yogo(2005)提出的Bonferroni检验方法,我们发现两个新的预测变量———权证与标的股票的交易金额比值和换手率比值,对于权证产品的收益率具有预测能力。     

Global modelling revisited

Reasons for the great impact of World Dynamics and Limits to Growth include their addressing the correct audience (the public), and the ability of systems dynamics clearly to handle and communicate information on complex and often little understood areas. Modelling projects should usually be global or national (not regional), draw heavily on mental and not just written and numerical databases, and have time horizons of perhaps 100 years. Sadly, critics of Worlds 2 and 3 have yet to come to grips with the fundamental messages presented there, although these messages are becoming increasingly vital.