Optimizing Stochastic Supply Chains via Simulation: What is an Appropriate Simulation Run Length

The most common solution strategy for stochastic supply-chain man-agement problems that are analytically intractable is simulation. But, how can we be sure that the optimal solution obtained by simulation is in fact the true optimal solution? In this paper we try to shed light on this question. We report the results of an extensive simulation study of a base-stock controlled production-inventory system. We tried different values of base-stock levels (R) to determine, via simulation, which was the value that minimized the total inventory holding and backordering costs per period. For 25 different cases (and 100 replications each), we compared the optimal solution obtained from simulation (Rs*) with the true optimal base-stock level (Ra*) obtained from an analytical result, with the goal of obtaining a lowerbound of 95% matches. Results show that when the traffic in-tensity increases, the run length necessary to achieve a minimum of 95% matches increases too, and when the backorder cost increases, the number of matches de-creases for each specific run length. In most of the cases simulated, 100,000 de-mands were enough to achieve reasonably reliable results.Postprint (published version

On Model-Based Systems Engineering for Design, Management, and Governance of Protective Systems

PresentationProtective systems failure can be catastrophic, and originates in management failure. These systems rely on a document-based approach, which involves handling disjointed artifacts that are expensive to maintain and may become inconsistent and obsolete. We propose a framework for managing process safety that pioneers the modeling of protective systems according to the tenors of model-based systems engineering (MBSE). The framework embeds management and governance, and harmonizes regulations and inconsistent industry guidelines. Potential users include enterprises and regulators in the chemical process safety industry and the energy sector. The framework starts the development of more sophisticated standards to prevent catastrophic protective systems failures

Health and Economic Benefits of Improved Injury Prevention and Trauma Care Worldwide

Objectives: Injury is a significant source of morbidity and mortality worldwide, and often disproportionately affects younger, more productive members of society. While many have made the case for improved injury prevention and trauma care, health system development in low- and middle-income countries is often limited by resources. This study aims to determine the economic benefit of improved injury prevention and trauma care in low- and middle-income countries. Methods: This study uses existing data on injury mortality worldwide from the 2010 Global Burden of Disease Study to estimate the number of lives that could be saved if injury mortality rates in low- and middle-income countries could be reduced to rates in high-income countries. Using economic modeling – through the human capital approach and the value of a statistical life approach – the study then demonstrates the associated economic benefit of these lives saved. Results: 88 percent of injury-related deaths occur in low- and middle-income countries. If injury mortality rates in low- and middle-income countries were reduced to rates in high-income countries, 2,117,500 lives could be saved per year. This would result in between 49 million and 52 million disability adjusted life years averted per year, with discounting and age weighting. Using the human capital approach, the associated economic benefit of reducing mortality rates ranges from $245 to$261 billion with discounting and age weighting. Using the value of a statistical life approach, the benefit is between 758 and 786 billion dollars per year. Conclusions: Reducing injury mortality in low- and middle-income countries could save over 2 million lives per year and provide significant economic benefit globally. Further investments in trauma care and injury prevention are needed

Barriers and facilitators to provide effective pre-hospital trauma care for road traffic injury victims in Iran: a grounded theory approach

BACKGROUND: Road traffic injuries are a major global public health problem. Improvements in pre-hospital trauma care can help minimize mortality and morbidity from road traffic injuries (RTIs) worldwide, particularly in low- and middle-income countries (LMICs) with a high rate of RTIs such as Iran. The current study aimed to explore pre-hospital trauma care process for RTI victims in Iran and to identify potential areas for improvements based on the experience and perception of pre-hospital trauma care professionals. METHODS: A qualitative study design using a grounded theory approach was selected. The data, collected via in-depth interviews with 15 pre-hospital trauma care professionals, were analyzed using the constant comparative method. RESULTS: Seven categories emerged to describe the factors that hinder or facilitate an effective pre-hospital trauma care process: (1) administration and organization, (2) staff qualifications and competences, (3) availability and distribution of resources, (4) communication and transportation, (5) involved organizations, (6) laypeople and (7) infrastructure. The core category that emerged from the other categories was defined as "interaction and common understanding". Moreover, a conceptual model was developed based on the categories. CONCLUSIONS: Improving the interaction within the current pre-hospital trauma care system and building a common understanding of the role of the Emergency Medical Services (EMS) emerged as key issues in the development of an effective pre-hospital trauma care process

Dead on arrival in a low-income country: results from a multicenter study in Pakistan

BACKGROUND: This study assessed the characteristics of dead on arrival (DOA) patients in Pakistan. METHODS: Data about the DOA patients were extracted from Pakistan National Emergency Department Surveillance study (Pak-NEDS). This study recruited all ED patients presenting to seven tertiary care hospitals during a four-month period between November 2010 and March 2011. This study included patients who were declared dead-on-arrival by the ED physician. RESULTS: A total of 1,557 DOA patients (7 per 1,000 visits) were included in the Pak-NEDS. Men accounted for two-thirds (64%) of DOA patients. Those aged 20-49 years accounted for about 46% of DOA patients. Nine percent (n = 72) of patients were brought by ambulance, and most patients presented at a public hospital (80%). About 11% of DOA patients had an injury. Factors significantly associated (p \u3c 0.05) with ambulance use were men (adjusted odds ratio [aOR] = 2.72), brought to a private hospital (OR = 2.74), and being injured (aOR = 1.89). Cardiopulmonary resuscitation (CPR) was performed on 6% (n = 42) of patients who received treatment. Those brought to a private hospital were more likely to receive CPR (aOR = 2.81). CONCLUSION: This study noted a higher burden of DOA patients in Pakistan compared to other resourceful settings (about 1 to 2 per 1,000 visits). A large proportion of patients belonging to productive age groups, and the low prevalence of ambulance and CPR use, indicate a need for improving the prehospital care and basic life support training in pakistan

Road Traffic Injury Is an Escalating Burden in Africa and Deserves Proportionate Research Efforts

Changing the mindset of road users in Africa will be a challenge, says the author, but many lives are at stake