Ricardo Izquierdo González (Hospital of Monforte de Lemos (Lugo)), Ramón María Dorrego García (Hospital of Monforte de Lemos (Lugo)), Pilar Rodríguez Ledo( Médico de Familia EOXI Lugo, Cervo e Monforte) and José Vicente Segura Heras (University Miguel Hernández of Elche).
Abstract. Background: The risk factors for abdominal aortic aneurysm (AAA) are present in many of the patients that attend our cardiology service. The aim of this study was the evaluation of the prospects of examining the abdominal aorta during our consultations and the relationship of AAA with risk factors and ischemic cardiopathy.
Methods: A descriptive transversal observational study was designed including 274 male patients aged ≥60 years, attended consecutively in the cardiology service, in which we studied the abdominal aorta and adjusted a logistic regression model to determine the risk factors associated with AAA.
Results: We were able to visualize and measure the abdominal aorta in 95.4% of cases in a fast and reliable way. The prevalence of AAA was 8.76%. 75% of patients with AAA presented ischemic heart disease. Patients with AAA were characterized by the presence of ischemic cardiopathy (Odds Ratio (OR): 4.27, 95% Confidence Interval (CI): 1.37–13.31, p = 0.012), dyslipidemia (OR: 4.99, 95% CI: 1, 07–23.31; p = 0.041), arterial hypertension (OR: 4.14,95% CI: 1.07–15.98, p = 0.039), and a longer history of smoking (OR: 1.03; 95% CI: 1002–1.054; p = 0.037).
Conclusions: The evaluation of the abdominal aorta during cardiology consultations is feasible with the standard resources. Patients treated in the cardiology service present a high prevalence of AAA. We have adjusted and validated a clinical prediction model based on risk factors that allows the identification, in the cardiology consult, of patients with the highest risk of suffering from AAA.
Keywords. Abdominal aortic aneurysm screening; Echocardiography; Cardiology clinic; Risk score.
Encarnación Algaba (University of Sevilla), Sylvain Béal (University Bourgogne Franche-Comté), Vito Fragnelli (University of Eastern Piedmont), Natividad Llorca (University Miguel Hernández of Elche) and Joaquin Sanchez-Soriano (University Miguel Hernández of Elche).
Abstract. We study the relationship between cooperative games which arise from very different situations. On the one hand, the labeled network game which is defined to study how to allocate a certain flow in a network among agents that control different parts of the network. On the other hand, the museum pass game which is defined to analyze how to distribute the profit generated by passes which provide visitors unlimited access to the participating museums. We establish that both problems are related in the sense that a museum pass game can be written as a labeled network game and almost all labeled network games can be written as museum pass games. We also point out that these classes of games
can be related to other classes of games, for which we provide a generic interpretation in terms of attributes and population.
Keywords. Game theory; Labeled network games; Museum pass games; Shapley value; Attribute situations; Approval voting.
Joaquin Sanchez-Soriano (University Miguel Hernández of Elch) and Natividad Llorca (University Miguel Hernández of Elche)
Abstract. Two-echelon models describe situations in which there are two differentiated groups of agents. Some examples of these models can be found in supply chain problems, transportation problems or two-sided markets. In this paper, we deal with two-sided transportation problems which can be used to describe a wide variety of logistic and market problems. We approach the problem from the perspective of cooperative games and study some solution concepts closely related to the game theoretical concept of core, but rather than focus specifically on the core of a transportation game, we introduce and study a new solution concept, a core catcher, which can be motivated by a kind of bounded rationality which can arise in these cooperative contexts.
Keywords. Cooperative games; two-echelon models; transportation games; core; core catcher; bounded rationality.
Vincent Charles (University of Buckingham) , Juan Aparicio (University Miguel Hernández of Elche) and Joe Zhu (UWorcester Polytechnic Institute)
Abstract. Data envelopment analysis (DEA) is a technique for identifying the best practices of a given set of decision-making units (DMUs) whose performance is categorized by multiple performance metrics that are classified as inputs and outputs. Although DEA is regarded as non-parametric, the sample size can be an issue of great importance in determining the efficiency scores for the evaluated units, empirically, when the use of too many inputs and outputs may result in a significant number of DMUs being rated as efficient. In the DEA literature, empirical rules have been established to avoid too many DMUs being rated as efficient. These empirical thresholds relate the number of variables with the number of observations. When the number of DMUs is below the empirical threshold levels, the discriminatory power among the DMUs may weaken, which leads to the data set not being suitable to apply traditional DEA models. In the literature, the lack of discrimination is often referred to as the “curse of dimensionality”. To overcome this drawback, we provide a simple approach to increase the discriminatory power between efficient and inefficient DMUs using the well-known pure DEA model, which considers either inputs only or outputs only. Three real cases, namely printed circuit boards, Greek banks, and quality of life in Fortune’s best cities, have been discussed to illustrate the proposed approach.
Keywords. Data envelopment analysis; Performance; Printed circuit boards; Banking; Best cities.
Luis Carretero (University Miguel Hernández of Elche) and José Valero (University Miguel Hernández of Elche).
Abstract. We study a one-dimensional ordinary differential equation modelling optical conveyor belts, showing in particular cases of physical interest that periodic solutions exist. Moreover, under rather general assumptions it is proved that the set of periodic solutions is bounded.
Keywords. Ordinary differential equations; Periodic solutions; Optical conveyor belts.
Juan Aparicio (University Miguel Hernández of Elche), Jesús T. Pastor (University Miguel Hernández of Elche) and C. A. Knox Lovell (University of Queensland,).
Abstract. A natural multiplicative efficiency measure for the Constant Returns to Scale proportional directional distance function (pDDF) is derived, relating its associated linear program to that of the well-known outputoriented radial efficiency measurement model. Based on this relationship, a traditional CCD (Caves, Christensen and Diewert) Malmquist index is introduced to show that, when it is based on the new efficiency measure associated with the pDDF, rather than on a radial efficiency measure associated with an oriented distance function, it becomes a Total Factor Productivity (TFP) index. This constitutes a new result, because heretofore the traditional CCD Malmquist index has not been considered a TFP index. Additionally, a new decomposition of the CCD Malmquist index is proposed that expresses productivity change as the ratio of two components, productivity change due to output change in the numerator and productivity change due to input change in the denominator. In an Appendix the efficiency measure is extended to include any returns to scale pDDF.
Keywords. Data envelopment analysis; Proportional directional distance function; Efficiency measure; Malmquist productivity index