Computational models of trust

Trust and reputation are key issues in the multi-agent systems domain. As in human societies, software agents must interact with other agents in settings where there is the possibility that they can be exploited. This suggests the need for theoretical and computational models of trust and reputation that can be used by software agents, and accordingly, much research has investigated this issue. The first part of this thesis investigates the conjecture that agents who make decisions in scenarios where trust is important can benefit from the use of a social structure, representing the social relationships that exist between agents. To this end, we present techniques that can be used by agents to initially build and then progressively update such a structure in the light of experience. As the agents interact with other agents they gather information about interactions and relationships in order to build the network of agents and to better understand their social environment. We also show empirical evidence that a trust model enhanced with a social structure representation, used to gather additional information to select trustworthy agents for an agent’s interactions, can improve the trust model’s performance. In the second part of this thesis, we concentrate on the context of coalition formation. Coalition stability is a crucial issue. Stability is the motivation of an agent’s refusal to break from the original coalition and form a new one. Lack of trust in some of the coalition members could induce one agent to leave the coalition. Therefore we address the current model’s limitation by introducing an abstract framework that allows agents to form distrust-free coalitions. Moreover we present measures to evaluate the trustworthiness of the agent with respect to the whole society or to a particular coalition. We also describe a way to combine the trust and distrust relationships to form coalitions which are still distrust-free

[Pulmonary thromboembolism and multimodality imaging: diagnostic work-up]

Pulmonary thromboembolism and multimodality imaging: diagnostic work-u

CDKL5, a novel MYCN-repressed gene, blocks cell cycle and promotes differentiation of neuronal cells

none7noMutations in the CDKL5 (cyclin-dependent kinase-like 5) gene are associated with a severe epileptic encephalopathy (early infantile epileptic encephalopathy type 2, EIEE2) characterized by early-onset intractable seizures, infantile spasms, severe developmental delay, intellectual disability, and Rett syndrome (RTT)-like features. Despite the clear involvement of CDKL5 mutations in intellectual disability, the function of this protein during brain development and the molecular mechanisms involved in its regulation are still unknown. Using human neuroblastoma cells as a model system we found that an increase in CDKL5 expression caused an arrest of the cell cycle in the G(0)/G(1) phases and induced cellular differentiation. Interestingly, CDKL5 expression was inhibited by MYCN, a transcription factor that promotes cell proliferation during brain development and plays a relevant role in neuroblastoma biology. Through a combination of different and complementary molecular and cellular approaches we could show that MYCN acts as a direct repressor of the CDKL5 promoter. Overall our findings unveil a functional axis between MYCN and CDKL5 governing both neuron proliferation rate and differentiation. The fact that CDKL5 is involved in the control of both neuron proliferation and differentiation may help understand the early appearance of neurological symptoms in patients with mutations in CDKL5.noneVALLI E; TRAZZI S; FUCHS C; ERRIQUEZ D; BARTESAGHI R; PERINI G; CIANI EVALLI E; TRAZZI S; FUCHS C; ERRIQUEZ D; BARTESAGHI R; PERINI G; CIANI

The impact of the 3-year ABSORB II trial results on my clinical practice: An Italian survey

Background: To evaluate how the 3-year results from the "A clinical evaluation to compare the safety, efficacy and performance of ABSORB everolimus eluting bioresorbable vascular scaffold (BVS) system against XIENCE everolimus eluting coronary stent system in the treatment of subjects with ischemic heart disease caused by de novo native coronary artery lesions" (ABSORB II) trial have influenced clinical practice among Italian interventional cardiologists. Methods: We performed a survey among 95 interventional cardiologists sending a brief questionnaire by electronic mail. We collected 65 replies and analysed the data. Results: The opinion of the operators regarding the two main endpoints of the study ABSORB II was conflicting. However, 66% of the operators considered at least one of the two co-primary endpoints (late lumen loss or vasomotion) unreliable and not reflecting clinical practice. Asking about an explanation for the negative results of the study, we found that the 91% of the operators considered the implantation technique the main limit of the ABSORB II. Furthermore, 74% of the operators affirmed that the results from the study did not decrease the number of scaffold implanted in their cath-lab. Conclusions: Absorb II trial did not influence clinical practice among Italian interventional cardiologists mainly due to the overall idea that the co-primary endpoints were not adequate to provide a robust evidence on device clinical safety and also because the lack of experience on device implantation may have influenced the outcomes

Comparison of Verapamil versus Heparin as Adjunctive Treatment for Transradial Coronary Procedures: The VERMUT Study

Objective: We sought to demonstrate that the combination of a local vasodilator (verapamil), modern materials, patent hemostasis, and intravenous anticoagulant only in the case of percutaneous coronary intervention, as compared to default heparin administration after sheath insertion, may optimize a combined endpoint, including radial artery oc­clusion (RAO), radial artery spasm (RAS), and access site complication. Methods: This is a prospective, single-center, double-blind randomized trial. Overall, 418 patients undergoing a transradial approach (TRA) for coronary procedures were randomized 1: 1 to receive intraradial verapamil (5 mg) or heparin (5,000 IU) after a 6-Fr sheath insertion. The primary outcome was the 24-h occurrence of RAO (ultrasound confirmation), access site complication, and RAS requiring the bailout administration of vasodilators. Results: The combined primary outcome occurred in 127 (30%) patients. It was significantly lower in patients randomized to verapamil as compared to others (26 vs. 35%, p = 0.03). This was mainly due to a significant reduction in RAS (3 vs. 10%, p = 0.006). The 24-h and 30-day occurrence of RAO did not differ between the study groups. Conclusion: Local administration of verapamil versus heparin reduces RAS, without increasing RAO, which appears to be strictly related to radial artery diameter and hemostasis time