Three Essays on Contagion Risk in Supply Chain

Firms often benefit when an unfavourable event befalls a rival, usually through a shift in demand. But sometimes negative events can adversely affect other firms in the industry, a phenomena referred to as contagion. While contagion can harm the supply chain by disrupting supply or demand, or increasing operating costs, it has not yet been studied in the area of supply chain risk management. Aiming to fill this gap, in the first essay I use real cases to conceptualize the process of contagion and apply related theories and literature to theorize the key factors contributing to contagion risk. The second essay examines the contagion effect of small to moderate events as opposed to extreme events, such as an explosion in a nuclear power plant, where contagion is clearly evident and documented. Finally, the third essay explores the conditions under which low-risk firms may benefit from investing in safety improvements for their higher-risk rivals. My dissertation contributes to the literature by recognizing the role of rivals’ safety in supply chain risk management

The Anti-Inflammatory Effect of Erythropoietin and Melatonin on Renal Ischemia Reperfusion Injury in Male Rats

Purpose: Renal ischemia reperfusion (IR) is an important cause of renal dysfunction. It contributes to the development of acute renal failure (ARF). The purpose of this study was to investigate the anti-inflammatory effect of erythropoietin (EPO) and melatonin (MEL), which are known anti-inflammatory and antioxidant agents, in IR-induced renal injury in rats. Methods: Male Wistar Albino rats were unilaterally nephrectomized and subjected to 45 min of renal pedicle occlusion followed by 24 h reperfusion. MEL (10mg/kg, i.p) and EPO (5000U/kg, i.p) were administered prior to ischemia. After 24 h reperfusion, blood samples were collected for the determination of total antioxidant capacity (TAC), malondialdehyde (MDA) and serum creatinine levels. Also, renal samples were taken for Immunohistochemical evaluation of Bcl2 and TNF-α (tumor necrosis factor-α) expression. Results: Ischemia reperfusion increased creatinine, TAC, MDA levels and TNF-α expression, also, IR decreased Bcl2 expression. Treatment with EPO or MEL decreased creatinine, MDA levels, and increased TAC level. Also, MEL up-regulated Bcl2 expression and down-regulated TNF-α expression compared with EPO. Conclusion: Treatment with EPO and MEL had a curative effect on renal IR injury. These results may indicate that MEL protects against inflammation and apoptosis better than EPO in renal IR injury

Aortic Valve Area and Strain Measurements by Cardiac MRI and Transthoracic Echocardiography in Severe Aortic Stenosis with Normal Left Ventricular Function

Background: Transthoracic echocardiography (TTE) is the recommended imaging technique for the evaluation of patients with aortic stenosis (AS). However, in cases with inconclusive findings, cardiac magnetic resonance (CMR) planimetry is used to grade AS severity. This study aimed to compare the results derived from TTE and CMR in patients with severe AS with normal left ventricular (LV) function.Methods: In a prospective study, 20 patients with severe AS were recruited and data derived from TTE and CMR modalities were compared with the archived records of 28 age- and sex-matched healthy controls. The data included aortic valve area (AVA), MRI-derived biventricular global strains, and TTE-derived global longitudinal strain (GLS). SPSS software was used to analyze the data with independent samples t test, intraclass correlation coefficient (ICC), and Pearson correlation. P<0.05 was considered statistically significant.Results: An excellent agreement was found in AVA values derived from CMR and TTE with an average ICC of 0.932 (95% CI=0.829-0.973). There was a significant difference in LV-GLS, LV global radial strain (GRS), right ventricular (RV) GRS, and RV global circumferential strain between the groups. A good correlation was found between CMR- and TTE-derived GLS with an average ICC of 0.721 (95% C=0.255-0.896). The mean aortic valve pressure gradient in TTE had a significant inverse linear correlation with LV-GRS in CMR (r=-0.537). All P values were <0.05.Conclusion: There was a good agreement between AVA and strain values derived from cardiac MRI and TTE. The myocardial strain was impaired in patients with severe AS and normal LV function and correlated with disease severity

Contagion risk: How stakeholders mediate the impact of rivals’ misfortunes on firms

AbstractThis study aims to investigate the dynamics of contagion and its impact on firms, specifically focusing on how a rival’s failure to control an event can have adverse consequences for other firms. Through a comprehensive analysis of relevant theories, literature, and real-world cases, the study identifies key factors that contribute to the contagion process and proposes a framework for assessing the associated risk. The research highlights the crucial role of stakeholders in mediating the effects of rivals’ misfortunes on other firms and emphasizes how stakeholders’ identities shape their risk evaluations, thereby affecting the occurrence of contagion. This study contributes to the existing literature by providing a conceptualization of the contagion process and introducing the concept of “stakeholder identity” within the context of organizational and operational risk management. The findings offer practical insights to firms by emphasizing the significance of contagion risk, which is often overlooked in operational risk management strategies. Additionally, the study provides valuable guidance on how firms can effectively assess their vulnerability to contagion, enabling them to proactively manage and mitigate their risk

Supply chain management through the stochastic goal programming model

Supply chain (SC) design problems are often characterized with uncertainty related to the decision-making parameters. The stochastic goal programming (SGP) was one of the aggregating procedures proposed to solve the SC problems. However, the SGP does not integrate explicitly the Manager's preferences. The aim of this paper is to utilize the chance constrained programming and the satisfaction function concept to formulate strategic and tactical decisions within the SC while demand, supply and total cost are random variables.Scopu

Developing a Robust Expansion Planning Approach for Transmission Networks and Privately-Owned Renewable Sources

Power system restructuring has changed transmission expansion planning (TEP) and caused many complications due to conflicting and contradictory objectives. The transmission capacity expansion would significantly affect the revenue of investor-owned renewable energy sources (RESs). Thus, the investment decisions on merchant RESs must be considered in the TEP studies conducted by the transmission system operator (TSO). In this regard, this paper aims to propose a multi-objective co-planning of investment in transmission networks and merchant RESs with three objective functions: minimizing the investment cost of newly deployed transmission lines, minimizing transmission congestion cost, and minimizing load curtailment in N-1 conditions. Moreover, the TSO guarantees a desirable rate of return for private investors to finance renewable energy projects. Further, a robust optimization (RO) technique is employed to cope with the uncertainties associated with demand and renewable energy production. Also, a posteriori multi-objective optimization algorithm, i.e., the non-dominated sorting genetic algorithm (NSGAII), is applied to solve the advanced optimization problem, followed by the fuzzy min-max method to acquire the final optimal solution. Finally, the IEEE RTS 24-bus test system is utilized to demonstrate the effectiveness and applicability of the suggested approach

The Effect of rTMS with Rehabilitation on Hand Function and Corticomotor Excitability in Sub-Acute Stroke

Objectives:&nbsp;Stroke is the leading cause of long-term disability. Hand motor impairment resulting from chronic stroke may have extensive physical, psychological, financial, and social implications despite available rehabilitative treatments. The best time to start treatment for stroke, is in sub-acute period. Repetitive transcranial magnetic stimulation (rTMS) is a method of stimulating and augmenting the neurophysiology of the motor cortex in order to promote the neuroplastic changes that are associated with motor recovery. The purpose of this study was to compare the effects of repetitive transcranial magnetic stimulation protocols plus routine rehabilitation on hand motor functions and hand corticomotor excitability in stroke patients with hemiplegia with pure routine rehabilitation programs. Methods: This study was a randomized clinical trial which was performed on 24 patients with hemiplegia who were randomly divided in to three groups. One group (n=7), received high frequency repetitive transcranial magnetic stimulation (Hf rTMS) on lesioned M1 with routine rehabilitation program, and the other group (n=7), received rehabilitation program with low frequency repetitive transcranial magnetic stimulation stimulation (Lf rTMS) on nonlesined M1, and a control group (n=10), who were given only routine rehabilitation programs. The treatment was performed for 10 sessions, three times peri-test, Post and follow-up about neurophysiological contralesional hemisphere evaluations using record of MEP wave indices by single pulse TMS, and assessing functional wolf test and hand grip power of disabled hand by dynamometer. Results: The results demonstrated that the rest MEP threshold reduction in experimental group which received high frequency magnetic stimulation was statistically significant (P<0.05). There was similar finding for active MEP threshold in the both high and low frequency but not in control group (P<0.05). Also there were more significant relation between obtained results from WOLF test and grip power with MEP mentioned parameters, in high frequency group, but not in low frequency and control group. Discussion: According to the results, However it seems that Hf rTMS combined with routin physiotherapy can significantly improve hand functions and brain neurophysiology via specifically increase of contralesional corticomotor excitability in sever stroke patients that is representative of the role of neuroplasticity in nonlesioned hemisphere but the hypothesis of movement improvement related cognitive balance can't be eliminated by exploring powerful approved effect of Hf rTMS on mood regulation

Percutaneous Autologous Bone Marrow-Derived Mesenchymal Stromal Cell Implantation Is Safe for Reconstruction of Human Lower Limb Long Bone Atrophic Nonunion

Objective Nonunion is defined as a minimum of a 9-month period of time since an injury with no visibly progressive signs of healing for 3 months. Recent studies show that application of mesenchymal stromal cells (MSCs) in the laboratory setting is effective for bone regeneration. Animal studies have shown that MSCs can be used to treat nonunions. For the first time in an Iranian population, the present study investigated the safety of MSC implantation to treat human lower limb long bone nonunion. Materials and Methods It is a prospective clinical trial for evaluating the safety of using autologus bone marrow derived mesenchymal stromal cells for treating nonunion. Orthopedic surgeons evaluated 12 patients with lower limb long bone nonunion for participation in this study. From these, 5 complied with the eligibility criteria and received MSCs. Under fluoroscopic guidance, patients received a one-time implantation of 20-50×106 MSCs into the nonunion site. All patients were followed by anterior-posterior and lateral X-rays from the affected limb, in addition to hematological, biochemical, and serological laboratory tests obtained before and 1, 3, 6, and 12 months after the implantation. Possible adverse effects that included local or systemic, serious or non-serious, and related or unrelated effects were recorded during this time period. Results From a safety perspective, all patients tolerated the MSCs implantation during the 12 months of the trial. Three patients had evidence of bony union based on the after implantation Xrays. Conclusion The results have suggested that implantation of bone marrow-derived MSCs is a safe treatment for nonunion. A double-blind, controlled clinical trial is required to assess the efficacy of this treatment (Registration Number: NCT01206179)