On Rohn's relative sensitivity coefficient of the optimal value for a linear-fractional program

summary:In this note we consider a linear-fractional programming problem with equality linear constraints. Following Rohn, we define a generalized relative sensitivity coefficient measuring the sensitivity of the optimal value for a linear program and a linear-fractional minimization problem with respect to the perturbations in the problem data. By using an extension of Rohn's result for the linear programming case, we obtain, via Charnes-Cooper variable change, the relative sensitivity coefficient for the linear-fractional problem. This coefficient involves only the measure of data perturbation, the optimal solution for the initial linear-fractional problem and the optimal solution of the dual problem of linear programming equivalent to the initial fractional problem

How to Solve a Multicriterion Problem for Which Pareto Dominance Relationship Cannot Be Applied? A Case Study from Medicine

Abstract. The most common way to deal with a multiobjective optimization problem is to apply Pareto dominance relationship between solutions. The question is: how can we make a decision for a multiobjective problem if we cannot use the conventional Pareto dominance for ranking solutions? We will exemplify this by considering a multicriterion problem for a medical domain problem. Trigeminal Neuralgia (TN) is a pain that is described as among the most acute known to mankind. TN produces excruciating, lightning strikes of facial pain, typically near the nose, lips, eyes or ears. Essential trigeminal neuralgia has questioned treatment methods. We consider five different treatment methods of the essential trigeminal neuralgia for evaluation under several criteria. We give a multiple criteria procedure using evolutionary algorithms for ranking the treatment methods of the essential trigeminal neuralgia for the set of all evaluation criteria. Results obtained by our approach using a very simple method are the same as the results obtained by applying weighted sum method (which requires lots of domain expert input). The advantage of the new proposed technique is that it does not require any additional information about the problem (like weights for each criteria in the case of weighted sum approach).

Language, culture and international exchange of virtual patients

<p>Abstract</p> <p>Background</p> <p>Language and cultural differences could be a limiting factor for the international exchange of Virtual Patients (VPs), especially for small countries and languages of limited circulation. Our research evaluated whether it would be feasible to develop a VP based educational program in our Romanian institution, with cases in English and developed in a non-Romanian setting.</p> <p>Method</p> <p>The participants in the research comprised 4^th year Romanian medical students from the Faculty of Medicine in Cluj-Napoca, Romania, with previous training exclusively in Romanian, good English proficiency and no experience with VPs. The students worked on eight VPs in two identical versions, Romanian and English. The first group (2010) of 136 students worked with four VPs developed in Cluj and the second group (2011) of 144 students with four VPs originally developed at an US University. Every student was randomly assigned two different VPs, one in Romanian and another in English. Student activity throughout the case, the diagnosis, therapeutic plan and diagnosis justification were recorded. We also compared student performance on the two VPs versions, Romanian and English and the student performance on the two sets of cases, originally developed in Romania, respectively USA.</p> <p>Results</p> <p>We found no significant differences between the students’ performance on the Romanian vs. English version of VPs. Regarding the students’ performance on the two sets of cases, in those originally developed in Romania, respectively in the USA, we found a number of statistically significant differences in the students’ activity through the cases. There were no statistically significant differences in the students’ ability to reach the correct diagnosis and therapeutic plan.</p> <p>Conclusion</p> <p>The development of our program with VPs in English would be feasible, cost-effective and in accordance with the globalization of medical education.</p

Iliadis Modeling

Multicriteria programming in medical diagnosis and treatment

Autoimmune diseases and vitamin D receptor Apa-I polymorphism are associated with vitiligo in a small inbred Romanian community

Vitiligo has been associated with the host's genetic profile, metabolic abnormality and immunostatus. The purpose of this study was to investigate the association of vitiligo with autoimmune diseases for 31 out of 39 subjects with vitiligo and their first-degree relatives living in a small Caucasian inbred rural community. They were compared with healthy individuals. A 2.28% prevalence of vitiligo was calculated and the presence of consanguine marriages (72.3%) was noted for this community. Our results indicate an increased prevalence of thyroidopathies, diabetes mellitus and rheumatoid arthritis in families with vitiligo. We also show that the Apa-I polymorphism of the vitamin D receptor gene is associated with vitiligo. This is the first study of its kind performed in Romania suggesting that the vitamin D receptor gene might play a role in the aetiopathogenesis of skin depigmentatio