Aggregation in Game Theoretical Situations

The thesis deals with the class of Aggregative Games, namely strategic form games where each payoff function depends on the corresponding player's strategy and on some aggregation among strategies of all involved players. The first part of the thesis is devoted to the multi-leader multi-follower equilibrium concept for the class of aggregative games: the considered game presents aymmetry between two groups of players, acting noncooperatively within the group and one group is the leader in a leader-follower hierarchical model. Moreover, as it happens in concrete situations, the model is affected by uncertainty and the game is considered in a stochastic context. Assuming an exogenous uncertainty affecting the aggregator, the multi-leader multi-follower equilibrium model is presented and existence results for the stochastic resulting game are obtained in the smooth case of nice aggregative games, where payoff functions are continuous and concave in own strategies, as well as in the general case of aggregative games with strategic substitutes. These results apply to the global emission game and the teamwork project game. Then, an investment in Common-Pool Resources is studied: the situation of many agents interested in a common-pool resource, like water resource, is modeled as an aggregative game and existence results of Nash equilibria are obtained with or without convexity-like assumptions. In the special case of quadratic return functions, the game is also considered under uncertainty i.e. when the possibility of a natural disaster with a given probability may occur. In the second part of the thesis, in line with the literature on additively separable aggregative games, a class of non cooperative games, called Social Purpose Games, is introduced. In this class of games the payoff of each player depends separately on his own strategy and on a function of the strategy profile, the aggregation function, which is the same for all players, weighted by an individual benefit parameter which enlightens the asymmetry between agents toward the social part of the benefit. The two parts of the payoff function represent respectively the individual and the social benefits. For the class of social purpose games it has been showed that they have a potential, providing also a comparison between the Nash equilibrium strategies and the social optimum strategies, namely when all the players agree in maximizing the aggregate profit. For social purpose games we study the existence of the so called coalition leadership equilibrium: it is a multi-leader multi-follower model where a cooperative behaviour is assumed between players of the leading group and they decide to maximize the aggregation of their payoffs. The rest of the players act noncooperatively. This kind of equilibrium presents a mixture of cooperative and noncooperative behaviour, situation that often occurs in many applicative examples. The weights affecting the aggregation function allow to derive explicit conditions under which the leading coalition is stable. An application to a water resource game is illustrated

Multi-Leader Multi-Follower Model with Aggregative Uncertainty

We study a non-cooperative game with aggregative structure, namely when the payoffs depend on the strategies of the opponent players through an aggregator function. We assume that a subset of players behave as leaders in a Stackelberg model. The leaders, as well the followers, act non-cooperatively between themselves and solve a Nash equilibrium problem. We assume an exogenous uncertainty affecting the aggregator and we obtain existence results for the stochastic resulting game. Some examples are illustrated

Long-term safety and efficacy of raloxifene in the prevention and treatment of postmenopausal osteoporosis: an update

The integrity of bone tissue and its remodeling that occurs throughout life requires a coordinated activity of osteoblasts and osteoclasts. The decreased estrogen circulating level during postmenopausal transition, with a prevalence of osteoclastic activity over osteoblastic activity, represents the main cause of bone loss and osteoporosis. Osteoporosis is a chronic disease requiring long-term therapy and it is important to evaluate the efficacy and safety of treatments over several years, as the fear of health risks is a common reason for discontinuing therapy. Raloxifene is a selective estrogen receptor modulator (SERM) leading to estrogen-agonist effects in some tissues and estrogen-antagonist effects in others. Raloxifene is effective to prevent and treat postmenopausal vertebral osteoporosis, with reduction of spine fractures and, in post-hoc analyses, non-spine fractures in high-risk subjects. Moreover, raloxifene reduces the risk of invasive breast cancer and improves the levels of serum lipoprotein but with an increased risk of venous thromboembolism and fatal stroke, without significant change in the incidence of coronary events. For these reasons the overall risk-benefit profile is favorable. Therefore, when considering the use of raloxifene in a postmenopausal woman, we should take into account the osteoporosis-related individual risk and weigh the potential benefits, skeletal and extra-skeletal, against the health risks

Unexplained cardiac arrest after near drowning in a young experienced swimmer: insight from cardiovascular magnetic resonance imaging

Cardiac magnetic resonance imaging (cMRI) is a well-established noninvasive imaging modality in clinical cardiology. Its ability to provide tissue characterization make it well suited for the study of patients with cardiac diseases. We describe a multi-modality imaging evaluation of a 45-year-old man who experienced a near drowning event during swimming. We underline the unique capability of tissue characterization provided by cMRI, which allowed detection of subtle, clinically unrecognizable myocardial damage for understanding the causes of sudden cardiac arrest and also showed the small damages caused by cardiopulmonary resuscitation

Editorial: The Canonical and Non-Canonical Endocannabinoid System as a Target in Cancer and Acute and Chronic Pain.

Editorial pape

Conservative Resectoscopic Surgery, Successful Delivery, and 60 Months of Follow-Up in a Patient with Endometrial Stromal Tumor with Sex-Cord-Like Differentiation

Uterine tumors with sex-cord-like differentiation are extremely rare types of uterine stromal neoplasm. These tumors were classified into two groups with considerable practical relevance because clinical behaviour of uterine tumor resembling ovarian sex cord tumor (UTROSCT) differs widely from its closely related endometrial stromal tumors with sex-cord-like elements (ESTSCLE). Treatment and prognosis of these tumors are unresolved issues because of the exiguous number of reported cases. We describe a rare case of endometrial stromal tumor with sex-cord-like differentiation successfully treated by resectoscopic surgery and conservation of the uterus, in an infertile patient affected by metrorrhagia. This procedure resulted in a pregnancy immediately after treatment and in a successful delivery. During 60 months of follow-up no evidence of recurrence was observed

Volumetric assessment of tumor size changes in pediatric low-grade gliomas: feasibility and comparison with linear measurements

Purpose: We report a retrospective comparison between bi-dimensional RANO criteria and manual volumetric segmentation (MVS) in pediatric low grade gliomas. Methods: MRI FLAIR or T1 post contrast images were used for assessment of tumor response. 70 patients were included in this single center study, for each patient two scans were assessed (“time 0” and “end of therapy”) and response to therapy was evaluated for both methods. Inter-reader variability and average time for volumetric assessment were also calculated. Results: 14 (20%) of the 70 patients had discordant results in terms of response assessment between the bi-dimensional measurements and MVS. All volumetric response assessments were in keeping with the subjective analysis of tumor (radiology report). Of the 14 patients, 6 had stable disease (SD) on MVS and progressive disease (PD) on 2D assessment, 5 patients had SD on MVS and partial response (PR) on 2D assessment, 2 patients had PD on MVS and SD on 2D assessment, and 1 patient had PR on MVS and SD on 2D analysis. The number of discordant results rises to 21(30%) if minor response is integrated in the response assessment. MVS was relatively fast and showed high interreader concordance. Conclusion: Our analysis shows that therapeutic response classification may change in a significant number of children by performing a volumetric tumor assessment. Furthermore MVS is not particularly time consuming and has very good inter-reader concordance

Assessment of coronary artery disease and calcified coronary plaque burden by computed tomography in patients with and without diabetes mellitus

Purpose: To compare the coronary atherosclerotic burden in patients with and without type-2 diabetes using CT Coronary Angiography (CTCA). Methods and Materials: 147 diabetic (mean age: 65 ± 10 years; male: 89) and 979 nondiabetic patients (mean age: 61 ± 13 years; male: 567) without a history of coronary artery disease (CAD) underwent CTCA. The per-patient number of diseased coronary segments was determined and each diseased segment was classified as showing obstructive lesion (luminal narrowing >50%) or not. Coronary calcium scoring (CCS) was assessed too. Results: Diabetics showed a higher number of diseased segments (4.1 ± 4.2 vs. 2.1 ± 3.0; p 400 (p < 0.001), obstructive CAD (37% vs. 18% of patients; p < 0.0001), and fewer normal coronary arteries (20% vs. 42%; p < 0.0001), as compared to nondiabetics. The percentage of patients with obstructive CAD paralleled increasing CCS in both groups. Diabetics with CCS ≤ 10 had a higher prevalence of coronary plaque (39.6% vs. 24.5%, p = 0.003) and obstructive CAD (12.5% vs. 3.8%, p = 0.01). Among patients with CCS ≤ 10 all diabetics with obstructive CAD had a zero CCS and one patient was asymptomatic. Conclusions: Diabetes was associated with higher coronary plaque burden. The present study demonstrates that the absence of coronary calcification does not exclude obstructive CAD especially in diabetics