Optimal route decision with a geometric ground-airborne hybrid model under weather uncertainty

Adverse weather is the dominant cause of delays in the National Airspace System (NAS). Since the future weather condition is only predictable with a certain degree of accuracy, managing traffic in the weather-affected airspace is a challenging task. In this paper, we propose a geometric model to generate an optimal combination of ground delay and route choice to hedge against weather risk. The geometric recourse model (GRM) is a strategic Probabilistic Air Traffic Management (PATM) model that generates optimal route choice, incorporating route hedging and en-route recourse to respond to weather change: hedged routes are routes other than the nominal or the detour one, and recourse occurs when the weather restricted airspace becomes flyable and aircraft are re-routed to fly direct to the destination. Among several variations of the GRM, we focus on the hybrid Dual Recourse Model (DRM), which allows ground delay as well as route hedging and recourses, when the weather clearance time follows a uniform distribution. The formulation of the hybrid DRM involves two decision variables - ground delay and route choice - and four parameters: storm location, storm size, maximum storm duration time, and ground-airborne cost ratio. The objective function has two components: expected total ground delay cost and expected total airborne cost. We propose a solution algorithm that guarantees to find the global optimum of the hybrid-DRM. Based on the numerical analysis, we find that ground-holding is effective only when combined with the nominal route. Otherwise, it is optimal to fly on the route determined by the DRM without ground delay. We also find the formula of the threshold ground-airborne cost ratio, which we call the Critical Cost Ratio (CCR), that determines the efficacy of ground delay: the higher the CCR, the more effective the strategies involving ground delay. We conclude that both ground delay and route hedging should be considered together to produce the best ATM decisions.     

Are we operating effectively? A lean analysis of operating theatre changeovers

Hospital operating theatres are a critical but costly resource in healthcare processes. Their efficiency and utilisation impact upon hospital finances, clinical effectiveness and patient outcomes. Operations management techniques have now been applied widely to optimise flow. An important challenge is to balance the needs of process flexibility, efficiency and work standardisation with clinical requirements. This paper applies operations management methods to analyse elective orthopaedic surgery at five international hospitals to describe the issues that affect operating theatre productivity. It utilises an innovative method of video analysis to observe patient changeovers over 29 days of surgery and data is analysed to understand the causes of variability and waste. The findings suggest that processes which are standardised via operations management methodologies can improve productivity in a process that exhibits wide variation in practice. There are apparent trade-offs associated with efficiency and clinical concerns such infection control, that lead to different standard process archetypes being utilised. Recommendations for standardising patient changeovers are provided.     

Japanese Consumption,External Disequilibrium and their Statistical Measurement

Georgescu-Roegen's work is usually divided into two categories, his earlier work on consumer and production theory and his later concern with entropy and bioeconomics beginning with his 1966 introductory essay to his collected theoretical papers published in the volume Analytical Economics. Most economists usually praise his earlier work on pure theory and ignore his later work which is highly critical of neoclassical economics. Those economists sympathetic to his later work usually take the position that he “saw the light” and gave up neoclassical theory some time in the 1960s to turn his attention to the issues of resource scarcity and social institutions. It is argued here that there is an unbroken path running from Georgescu's work in pure theory in the 1930s, 1940s, and 1950s, through his writings on peasant economies in the 1960s, leading to his preoccupation with entropy and bioeconomics in the last 25 years of his life. That common thread is his preoccupation with “valuation.” The choices our species makes about resource use and the distribution of economic output depends upon our valuation framework. Georgescu-Roegen's work begins in the 1930s with a critical examination of the difficulties with the hedonistic valuation framework of neoclassical economics, moves in the 1960s to the conflict between social and hedonistic valuation, and culminates in the 1970s and 1980s with his examination of the conflict between individual, social, and environmental values. This paper traces the evolution of Georgescu-Roegen's thought about valuation and the environmental and social policy recommendations which arise out of his bioeconomic framework.     

The Impact of Retirement on Household Leisure Expenditures

Household leisure expenditures for retired and near‐retired households were examined in order to better understand the dynamics associated with the move to retirement status. Data from the 1995 Consumer Expenditure Survey indicated that retirement, total expenditures, and education had positive impacts on leisure expenditures. For retired households, greater total expenditures and education increased expenditures, while age and the presence of earned income decreased expenditures. For near‐retired households, greater total expenditures, education, and the presence of asset income significantly increased leisure expenditures.     

The impact of SARS on China's human resources: implications for the labour market and level of unemployment in the service sector in Beijing,Guangzhou and Shanghai

In this paper, we examine the effects of SARS (Severe Acute Respiratory Syndrome) on China's human resources, its labour-market and its level of employment and unemployment, looking specifically at what was one of its economically most vulnerable points, the hotel industry. The paper hypothesizes that the greatest impact would be on human resources in the service-industries and on particular sub-sectors, such as employment in hotels, located in three main cities in the PRC, in Beijing, Guangzhou and Shanghai, catering to both overseas as well as domestic tourism. It tentatively concludes that the almost dramatic demand and supply ‘shocks’ may have directly affected both the demand for and the supply of labour in the sub-sector, with discernable employment consequences.     

Procurement of logistics services and sustainable development in Europe: Fields of activity and empirical results

This paper strives to answer the general question; how far purchasers of logistics services take into account aspects of sustainable development. Modeled on the German Sustainable Development Strategy, which is based on the EU Sustainable Development plan, five fields of activity are defined: the reduction of transport intensity and emission, the reduction of land use, the choice of carrier under consideration of sustainable aspects, the permanent improvement of working conditions, and the enhancement of qualified employment. Then, propositions for purchasing companies of logistics services are developed, which contribute to safeguard ecological as well as social sustainability. In order to conduct an explorative study, a questionnaire was sent to 750 purchase and logistics managers. It was found that purchasing companies place high value on ecological and social aspects. But the perceived importance is not associated with purchasing companies' own contributions to logistics service providers' sustainable activities. Additionally, it was seen that purchasing companies exert only a minor influence on logistics service providers regarding ecologically and socially sustainable actions. A fundamental precondition for a sustainably oriented procurement of logistics services can be seen in the purchasing companies' awareness of the need for integrating sustainable aspects in economic decisions.     

MNE home country cultural norms and conflict strategy fit in transnational business contract disputes

The increasing frequency and complexity of transnational business relationships has been commensurate with an increase in contractual disputes. In such situations, home country cultural norms will often influence how MNEs resolve contractual disputes in foreign markets. This begs the question: does fit between an MNE's choice of conflict strategy and its home country cultural norms affect monetary payouts (costs) in transnational business contract disputes? We apply organizational imprinting theory and the fit paradigm to a model employing data from U.S. court cases involving 316 MNEs from 47 countries. We find that choosing a conflict strategy that fits home country cultural norms will result in higher monetary payouts for MNEs. Additionally, cultural distance, but not legal distance, enhances the positive relationship between MNE conflict strategy fit and monetary payouts. Implications and future research directions are discussed.     

Earnings Management through Specific Accruals and Discretionary Expenses: Evidence from U.S. Agribusiness Firms

This study examines both accruals based earnings management (AEM) and real earnings management (REM) in U.S. agribusinesses. In particular, the focus is on agribusinesses that report low earnings quality, defined as firms with extreme level of accruals compared to their peers. The cross‐sectional modified Jones model (Jones 1991; Dechow et al 1995) is used to test for AEM. To capture REM practices, we implement the discretionary expenses model by Roychowdhury (2006). We find evidence of AEM and find no evidence of REM in agribusinesses. In addition, our results show that managers might be managing earnings through specific accruals doubtful accounts receivable provisions and special items.