ABSTRACT
The safety assessment of cyber-physical systems (CPSs) requires tremendous effort, as the complexity of cyber-physical systems is increasing. A well-known approach for the safety assessment of CPSs is fault injection (FI). The goal of fault injection is to find a catastrophic fault that can cause the system to fail by injecting faults into it. These catastrophic faults are less likely to occur, and finding them requires tremendous labor and cost. In this study, we propose a reinforcement learning (RL)-based method to automatically configure faults in the system under test and to find catastrophic faults in the early stage of system development at the model level. The proposed method provides a guideline to utilize high-level domain knowledge about a system model for constructing the reinforcement learning agent and fault injection setup. In this study, we used the system (safety) specification to shape the reward function in the reinforcement learning agent. The reinforcement learning agent dynamically interacted with the model under test to identify catastrophic faults. We compared the proposed method with random-based fault injection in two case studies using MATLAB/Simulink. Our proposed method outperformed random-based fault injection in terms of the severity and number of faults found.
ABSTRACT
Objectives: This study aimed to compare the colonization of Enterococcus faecalis (E. faecalis), Escherichia coli (E. coli), Streptococcus mutans (S. mutans) and Staphylococcus aureus (S. aureus) isolated from the oral cavity on different suture materials used in oral implantology. Materials and Methods: Patients scheduled for implant surgery were included in this study. After flap approximation, the surgical site was sutured using silk, nylon, polyglactin 910 (Vicryl®) and triclosan-coated polyglactin 910 (Vicryl® Plus) sutures in a randomized order. Seven days after surgery, the sutures were removed and incubated in bile esculin agar (for E. faecalis), MacConkey agar (for E. coli), mitis salivarius agar (for S. mutans), and mannitol salt agar (for S. aureus) at 37°C for 24 h. The colonies were then counted. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: Vicryl® sutures showed the highest accumulation of E. faecalis, followed by Vicryl® Plus, nylon, and silk. There was no significant difference between nylon and silk (P=0.5) or between Vicryl® and Vicryl® Plus (P=0.4). Vicryl® Plus sutures showed the highest accumulation of E. coli followed by Vicryl®, silk and nylon (P<0.01). Vicryl® sutures showed the highest accumulation of S. mutans, followed by Vicryl® Plus, silk, and nylon. Vicryl® Plus sutures showed the highest accumulation of S. aureus, followed by Vicryl®, nylon, and silk. Conclusion: Nylon sutures showed the least microbial accumulation. Vicryl® and triclosan-coated Vicryl® Plus sutures had no advantage over the commonly used silk sutures in decreasing the number of bacteria.
ABSTRACT
BACKGROUND: Entomotoxicology as a subset of forensic entomology can be used by analysis of carcass feeding insects to detecting of drugs or toxins, as well as the cause and manner of death in cases of ante-mortem drugs intoxication. Morphine is one of the deacetylate metabolites of heroin. The aim of this study was to determine the presence and quantity of morphine in insects on the carcass and compare them with decomposing carcass. METHODS: Field of this study was in Chalabeh District and toxicological tests were carried out at the Department of Forensic Toxicology, Legal Medicine Center, Kermanshah, Iran in 2017. Morphine was inoculated into live rabbit as experimental model at concentrations of 12.5, 25, 50mg/ml, similar to those normally encountered in human overdoses, then quality and quantity of morphine were determined in insects such as Chrysomya albiceps (as the first wave of insect succession on human cadavers) fed on carcass. RESULTS: Quantitative assessment at larvae showed that morphine was detected in all larvae (feeding and post feeding stage) fed on tissues from carcasses administered morphine, except for post-feeding larvae from R1 which received 12.5mg/ml dosage of morphine. CONCLUSION: Necrophagous insects are an indicator on the scene of crime and a potential source of information about the antemortem situation. Detection of drug in insects which is actually a reflection of the cause of death is possible.
ABSTRACT
Postdural puncture headache and cerebral subdural hematoma are among complications of spinal anesthesia with some common characteristics; however misdiagnosis of these two could result in a catastrophic outcome or prevent unwanted results by urgent interventions. With the purpose of increasing awareness of such complications and a speedy diagnosis, we report two cases of postspinal anesthesia headache that was timely diagnosed as cerebral subdural hematoma and prevented the likelihood of a disastrous outcome.
