Fuzzy models for group decision making and applications to e-learning and recommender systems

2016 - 2017The work presented in the Ph.D. thesis deals with the definition of new fuzzy models for Group Decision Making (GDM) aimed at improving two phases of the decision process: preferences expression and aggregation. In particular a new preferences model named Fuzzy Ranking has been defined to help decision makers express fuzzy statements on available alternatives in a simple and meaningful form, focusing on two alternatives at a time but, at the same time, without losing the global picture. This allows to reduce inconsistencies with respect to other existing models. Moreover a new preference aggregation model guided by social influence has been described. During a GDM process, in fact, decision makers interact and discuss each other exchanging opinions and information. Often, in these interactions, those with wider experience, knowledge and persuasive ability are capable of influencing the others fostering a change in their views. So, social influence plays a key role in the decision process but, differently from other aspects, very few attempts to formalize its contribution in preference aggregation and consensus reaching have been made till now. In order to validate the defined models, they have been instantiated in two application contexts: e- Learning and Recommender Systems. In the first context, they have been applied to the peer assessment problem in massive online courses. In such courses, the huge number of participants prevents their thorough evaluation by the teachers. A feasible approach to tackle this issue is peer assessment, in which students also play the role of assessor for assignments submitted by others. But students are unreliable graders so peer assessment often provides inaccurate results. By leveraging on defined GDM models, a new peer assessment model aimed at improving the estimations of student grades has been proposed. With respect to Recommender Systems, the group recommendation issue has been tackled. Instead of generating recommendations fitting individual users, Group Recommender Systems provide recommendations targeted to groups of users taking into account the preferences of any (or the majority of) group members together. The majority of existing approaches for group recommendations are based on the aggregation of either the preferences or the recommendations generated for individual group members. Customizing the defined GDM models, a new model for group recommendations has been proposed that also takes into account the personality of group members, their interpersonal trust and social influence. The defined models have been experimented with synthetic data to show how they operate and demonstrate their properties. Once instantiated in the defined application contexts, they have been also experimented with real data to measure their performance in comparison to other context-specific methods. The obtained results are encouraging and, in most cases, better than those achieved by competitor methods. [edited by author]XVI n.s

Fifth International Workshop on Adaptive Learning via Interactive, Collaborative and Emotional Approaches (ALICE 2015)

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Personalization and Contextualization of Learning Experiences based on Semantics

Context-aware e-learning is an educational model that foresees the selection of learning resources to make the e-learning content more relevant and suitable for the learner in his/her situation. The purpose of this paper is to demonstrate that an ontological approach can be used to define leaning contexts and to allow contextualizing learning experiences finding out relevant topics for each context. To do that, we defined a context model able to formally describe a learning context, an ontology-based model enabling the representation of a teaching domain (including context information) and a methodology to generate personalized and context-aware learning experiences starting from them. Based on these theoretical components we improved an existing system for personalized e-learning with contextualisation features and experimented it with real users in two University courses. The results obtained from this experimentation have been compared with those achieved by similar systems

Fuzzy Group Decision Making for Influence-Aware Recommendations

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Group Recommender Systems are special kinds of Recommender Systems aimed at suggesting items to groups rather than individuals taking into account, at the same time, the preferences of all (or the majority of) members. Most existing models build recommendations for a group by aggregating the preferences for their members without taking into account social aspects like user personality and interpersonal trust, which are capable of affecting the item selection process during interactions. To consider such important factors, we propose in this paper a novel approach to group recommendations based on fuzzy influence-aware models for Group Decision Making. The proposed model calculates the influence strength between group members from the available information on their interpersonal trust and personality traits (possibly estimated from social networks). The estimated influence network is then used to complete and evolve the preferences of group members, initially calculated with standard recommendation algorithms, toward a shared set of group recommendations, simulating in this way the effects of influence on opinion change during social interactions. The proposed model has been experimented and compared with related works

a web based knowledge hub for special and inclusive education

The need of a common environment where to share information and knowledge is of particular interest in the field of special education not only to support the access to a large amount of available information (along with the ability to derive value from this information) but also to foster synergistic actions involving different special education operators. In this paper we present the results of a research aimed at defining a Web-based environment for special edu-cation providing, to operators of the field, personalized in-formation and digital assets covering both their expressed and latent information needs. Offered personalization features are based on the definition and the implementation of a hybrid recommender system based on a mix of cognitive and collaborative approaches, the first based on the similarities among digital objects, the latter leveraging on similarities among user profiles. By combining these two approaches the system is able to provide meaningful but not obvious recommendations with a fair level of serendipity. The encouraging results of an experimentation with real users are also reported

Expandable intramedullary nailing and platelet rich plasma to treat long bone non-unions

Background Roentgenographic and functional outcomes of expandable self locking intramedullary nailing and platelet rich plasma (PRP) gel in the treatment of long bone non-unions are reported. Materials and methods Twenty-two patients suffering from atrophic diaphyseal long bone non-unions were enrolled in the study. Patients were treated with removal of pre-existing ardware, decortication of non-union fragments, and fixation of pseudoarthrosis with expandable intramedullary nailing (FixionTM, Disc’O Tech, Tel Aviv, Israel). At surgery, PRP was placed in the pseudoarthrosis rim. Results The thirteen-month follow-up showed 91% (20/22 patients) of patients attaining bony union. The average time to union was 21.5 weeks. No infection, neurovascular complication, rotational malalignment, or limb shortening [4 mm were observed. The healing rate of non-unions was comparable to that observed in previous studies but with a lower complication frequency. Conclusions The combined use of self locking intramedullary nailing and PRP in the management of atrophic diaphyseal long bone non-unions seems to produce comparable results with less complications than previously reported. Further data are warranted to investigate the single contribution of PRP gel and Fixion nail

Ontology-driven Generation of Training Paths in the Legal Domain

This paper presents a methodology for helping citizens obtain guidance and training when submitting a natural language description of a legal case they are interested in. This is done via an automatic mechanism, which firstly extracts relevant legal concepts from the given textual description, by relying upon an underlying legal ontology built for such a purpose and an enrichment process based on common-sense knowledge. Then, it proceeds to generate a training path meant to provide citizens with a better understanding of the legal issues arising from the given case, with corresponding links to relevant laws and jurisprudence retrieved from an external legal repository. This work de-scribes the creation of the underlying legal ontology from existing sources and the ontology integration algorithm used for its production; besides, it details the generation of the training paths and reports the results of the preliminary experimentation that has been carried out so far. This methodology has been implemented in an Online Dispute Resolution (ODR) system that is part of an Italian initiative for assisted legal mediation

Problems, complications, and reinterventions in 4893 onlay humeral lateralized reverse shoulder arthroplasties, a systematic review: part II-problems and reinterventions

Background: Several modifications to the original Grammont reverse shoulder arthroplasty (RSA) design have been proposed to prevent distinctive issues, such as both glenoid and humeral lateralization. The aim of this systematic review was to determine rates of problems, complications, reoperations, and revisions after onlay lateralized humeral stem RSA, hypothesizing that these are design related. Methods: This systematic review was performed in accordance with the PRISMA statement guidelines. A literature search was conducted (1 January 2000 to 14 April 2020) using PubMed, Cochrane Reviews, Scopus, and Google Scholar, employing several combinations of keywords: "reverse shoulder arthroplasty," "reverse shoulder prosthesis," "inverse shoulder arthroplasty," "inverse shoulder prosthesis," "problems," "complications," "results," "outcomes," "reoperation," and "revision." Results: Thirty-one studies with 4893 RSA met inclusion criteria. The 892 postoperative problems and 296 postoperative complications represented overall problem and complication rates of 22.7% and 7.5%, respectively. Forty-one reoperations and 63 revisions resulted, with overall reoperation and revision rates of 1.7% and 2.6%, respectively. Conclusions: Problem, complication, and reintervention rates proved acceptable when implanting a high humeral lateralization stem RSA. The most frequent problem was scapular notching (12.6%), and the most common postoperative complication was scapular stress fracture (1.8%). An overall humeral complication rate of 1.9% was identified, whereas no humeral fractures or stem loosening were reported with short stems. Infections (1.3%) were the most common reason for component revision, followed by instability (0.8%). Level of evidence: Systematic review IV

Idiopathic pulmonary fibrosis and coronary artery disease

Idiopathic pulmonary fibrosis (IPF) is defined as a chronic fibrosing interstitial disease of unknown cause, limited to the lungs, and associated with the histopathologic and/or radiologic pattern of usual interstitial pneumonia (UIP); it generally progresses into respiratory failure and death. Although progression of the disease is the most common cause of death, there are increasing reports of its association with other pathologies has been reported: e.g., IPF patients seem more susceptible to cardiovascular diseases. Therefore, other pathologies might also influence the natural course. In this paper, we describe a case of IPF and coronary artery disease (CAD). We emphasize the importance of cardiopulmonary exercise test (CPET) as a useful procedure to monitor disease progression in IPF patients. We also stress the importance of a careful analysis of variables measured for an accurate interpretation of the clinical picture and an improvement of the clinical management of patients. Moreover, we suggest that a careful assessment of CPET parameters may additionally help in the early detection of high cardiovascular ischemic risk