Ayman Ghoneim

Information Sharing in the Iterated Prisoner's Dilemma Game

In the iterated prisoners dilemma (IPD) game, players normally have access to their own history, without being able to communicate global information. In this paper, we introduce information sharing among players of the IPD game. During the co-evolutionary process, players obtain access, through information sharing, to the common strategy adopted by the majority of the population in the previous generation. An extra bit is added to the history portion in the strategy chromosome. This extra bit holds a value of 0 if the decisions to cooperate were greater than the decisions to defect in the last generation and 1 if otherwise. We show that information sharing alters the dynamics of the IPD game

Comparative study between sugammadex and neostigmine in neurosurgical anesthesia in pediatric patients

Background: Postoperative recurarization remains a risk following the use of the conventional neuromuscular blocking agents. In addition, none of the commonly used reversal agents, such as neostigmine or edrophonium are capable of reliably reversing profound blockade. The present comparative and randomized study investigated the use of sugammadex for reversing profound neuromuscular blockade (NMB) in pediatric neurosurgical patients undergone posterior fossa tumor excision. Patients and Methods: Forty pediatric patients undergoing elective craniotomy for posterior fossa tumor excision were randomly divided into either of neostigmine or sugammadex group in which muscle relaxant was reversed at the end of anesthesia either with neostigmine 0.04 mg/kg added to atropine 0.02 mg/kg or sugammadex 4 mg/kg alone, respectively. The primary endpoint was the time from the administration of sugammadex or neostigmine to recovery of the train of four (TOF) ratio to 90% after rocuronium-induced neuromuscular block. Unpaired t-test was used to compare continuous variables between groups. Meanwhile, repeated ANOVA was used to detect intragroup differences. Results: Patients in sugammadex group attained a TOF ratio 90% in statistically shorter time (1.4 ± 1.2 min) than those in neostigmine group (25.16 ± 6.49 min) for reversal of the rocuronium. Mean arterial pressure and heart rate were significantly higher in neostigmine group at 2, 5 and 10 min after administration of the reversal agents and returned nonsignificantly different after that. With no recurarization in any patient throughout the study period. Conclusion: Sugammadex rapidly and effectively reverses rocuronium-induced NMB in pediatric patients undergoing neurosurgery when administered at reappearance of T2 of TOF at dose 4 mg/kg.

Comparative study between computed tomography guided superior hypogastric plexus block and the classic posterior approach: A prospective randomized study.

Context: The classic posterior approach to superior hypogastric plexus block (SHPB) is sometimes hindered by the iliac crest or a prominent transverse process of L5. The computed tomography (CT) – guided anterior approach might overcome these difficulties. Aims: This prospective, comparative, randomized study was aimed to compare the CT guided anterior approach versus the classic posterior approach. Settings and Design: Controlled randomized study. Materials and Methods: A total of 30 patients with chronic pelvic cancer pain were randomized into either classic or CT groups where classic posterior approach or CT guided anterior approach were done, respectively. Visual analog score, daily analgesic morphine consumed and patient satisfaction were assessed just before the procedure, then, after 24 h, 1 week and monthly for 2 months after the procedure. Duration of the procedure was also recorded. Adverse effects associated with the procedure were closely observed and recorded. Statistical Analysis Used: Students t-test was used for comparison between groups. Results: Visual analog scale and morphine consumption decreased significantly in both groups at the measured times after the block compared with the baseline in the same group with no significant difference between both groups. The procedure was carried out in significantly shorter duration in the CT group than that in the classic group. The mean patient satisfaction scale increased significantly in both groups at the measured times after the block compared with the baseline in the same group. The patients in the CT groups were significantly more satisfied than those in classic group from day one after the procedure until the end of the study. Conclusions: The CT guided approach for SHPB is easier, faster, safer and more effective, with less side-effects than the classic approach.

The Effect of Risk Perceived Payoffs in Iterated Interdependent Security Games

Interdependent security IDS refers to a class of problems that involve making security investment decisions under uncertainty arising from the interdependency between the actions of different decision making entities in the system. Such problems arise in many real world situations such as cyber, airline and homeland security and epidemics. IDS games provide a framework to study the behaviour of decision-makers in such environments. This paper presents a study of the IDS game dynamics in a simulation setting when the payoffs are varied based on different risk attitude functions using the concept of expected utilities. A special case of iterated IDS games is considered where the assumption of complete loss immunity, in the case where all agents cooperate in investing in their own security, is relaxed by introducing a small stochastic loss term in the payoff. The simulations are carried out using an evolutionary game-theoretic framework where strategies are evolved based on the payoffs accumulated over homogeneous iterated encounters. The results of the simulations suggest that the level of investments are reduced when agents take a risk-averse or risk-taking view of the game in comparison to risk-neutral view.

Investigating alliance dynamics using a co-evolutionary iterated prisoner’s dilemma with an exit option

Evolutionary games are used in understanding the complex dynamics of real life situations. The iterated prisoners dilemma game with exit option was used in modeling strategic alliances. The model was solved as an optimization problem, and several observations were considered as to how partners are behaving in the alliance, and what factors are affecting the alliances cooperation level. In this paper we introduce an evolutionary version of the iterated prisoners dilemma game with exit option to better understand alliance activity and investigate whether the observations from the mathematical solution continue to hold in the evolutionary environment. The results reveal that in some cases there is a significant difference in the evolutionary dynamics from that predicted by the mathematical solution. The mathematical model was found to be inadequate for alliances which use history information to make their future decisions.

A multiobjective distance separation methodology to determine sector-level minimum separation for safe air traffic scenarios

A precursor question to increase the capacity of an airspace is to determine the minimum distance separation required to make this airspace safe. A methodology to answer this question is proposed in this paper. The methodology takes sector volume, number of crossings and crossing angles of routes, and the number of aircraft as input, and generate air traffic scenarios which satisfy the input values. A stochastic multi-objective optimization algorithm is then used to optimize separation values. The algorithm outputs the set of non-dominated solutions representing the trade-off between separation values and the best attainable target level of safety. The results show that the proposed methodology is successful in determining the minimum distance separation values required to make an air traffic scenario safe from a collision risk perspective, and in illustrating how minimum separation values are affected by different sector/traffic characteristics.

Safety and consumption of sevoflurane versus desflurane using target controlled anesthesia in children

Abstract Background Recently a concept of target controlled inhalational anesthesia (TCA) is introduced in which the fresh gas flow and its composition are automatically delivered to the patients with the least possible flow. The aim of this study is to compare safety, consumption and cost of both sevoflurane and desflurane when delivered by target controlled anesthesia (TCA) using fully closed circuit conditions. Patient and method After approval of the hospital review board and obtaining parental informed consent, 60 pediatric patients aged 2–12 were selected. The patients were classified into two groups according to the anesthetic used S Group (n = 30) in which sevoflurane D Group (n = 30): in which desflurane was used. Both were delivered by auto control mode of Zeus machine. Anesthetic agent and O2 consumption, cost and number of adjustments were assessed. Blood samples were obtained preoperatively and at 24, 48 and 72 h after the end of surgery for measuring serum creatinine, BUN, AST and ALT. Twenty-four hour urine samples were collected for 3 consecutive days to measure glucose, microprotein and creatinine for the estimation of creatinine clearance. Results This study revealed that sevoflurane group had a lower O2, anesthetic consumption and cost than desflurane group. Also both groups had higher levels of serum urea and creatinine together with urinary microproteins and glucose in the first three post-operative days compared to preoperative values which indicates minor tubular insult. However there was no statistically significant difference between the two groups. Conclusion Sevoflurane is as safe as desflurane when delivered by auto control mode of Zeus machine with decreased anesthetic consumption and cost.