A unified framework for traditional and agent-based social network modeling

In the last sixty years of research, several models have been proposed to explain (i) the formation and (ii) the evolution of networks. However, because of the specialization required for the problems, most of the agent-based models are not general. On the other hand, many of the traditional network models focus on elementary interactions that are often part of several different processes. This phenomenon is especially evident in the field of models for social networks. Therefore, this chapter presents a unified conceptual framework to express both novel agent-based and traditional social network models. This conceptual framework is essentially a meta-model that acts as a template for other models. To support this meta-model, the chapter proposes a different kind of agent-based modeling tool that we specifically created for developing social network models. The tool the authors propose does not aim at being a general-purpose agent-based modeling tool, thus remaining a relatively simple software system, while it is extensible where it really matters. Eventually, the authors apply this toolkit to a novel problem coming from the domain of P2P social networking platforms

Advanced Agent-Based Modeling for Social Networks

Agent-based modeling and simulation have been successfully applied to problems emerging from social sciences and could be profitably used also for the online social networks. However, the tools presently available for agent-based modeling do not offer specific support for social network models. In the present work, we present a unified conceptual framework to develop both novel agent-based and traditional social network models. This conceptual framework is essentially a meta-model to express the other models. In addition, we designed a domain-specific language to formulate the models in an executable way, so that simulations can be performed effortlessly. The language aims at being expressive and powerful for those with a strong background in computing, and yet simple and easy to learn for those with different expertises. We also developed a software platform that can execute such models in an agent-oriented context, providing effective support for large networks. Moreover, the platform hides most of the complexity of running the simulations on remote server-class machines. We validated out approach by translating several traditional models in our meta-model, verifying that the expected features of the models are maintained. The results show that our approach is successful in providing a friendly and easy environment to perform agent-based simulations over social networks, simulations that are of interest both to develop models and to study the results of the models themselves. Then, considering the favorable results we obtained, we applied our platform to the still open problem of creating an entirely distributed social networking system, which, as compared to the centralized ones, yields relevant advantages as far as privacy and resilience are concerned. We developed several models to help us in the understanding of the many issues that a P2P social networking system would have when deployed, and specifically of the well-known issue of the availability of rare resources. Through simulations, we found some criteria for the design of distributed social networks and some operation conditions which may result in a satisfactory user experience in terms of reduced delays in the propagation of information. Consequently, these results allow us to develop now a distributed social networking system optimized by means of our simulations

A Dynamic Programming Framework for Optimal Planning of Redundant Robots Along Prescribed Paths With Kineto-Dynamic Constraints

Off-line optimal planning of trajectories for redundant robots along prescribed task space paths is usually broken down into two consecutive processes: first, the task space path is inverted to obtain a joint-space path, then, the latter is parametrized with a time law. If the two processes are separated, they cannot optimize the same objective function, ultimately providing sub-optimal results. In this paper, a unified approach is presented where dynamic programming is the underlying optimization technique. Its flexibility allows accommodating arbitrary constraints and objective functions, thus providing a generic framework for optimal planning of real systems. To demonstrate its applicability to a real world scenario, the framework is instantiated for time-optimality. Compared to numerical solvers, the proposed methodology provides visibility of the underlying resolution process, allowing for further analyses beyond the computation of the optimal trajectory. The effectiveness of the framework is demonstrated on a real 7-degrees-of-freedom serial chain. The issues associated with the execution of optimal trajectories on a real controller are also discussed and addressed. The experiments show that the proposed framework is able to effectively exploit kinematic redundancy to optimize the performance index defined at planning level and generate feasible trajectories that can be executed on real hardware with satisfactory results

The relationship between digital technologies and the circular economy: a systematic literature review and a research agenda

Digital technologies are widely recognised as crucial for promoting the circular economy in industry. However, there still needs to be clearer guidance for industrial practitioners on properly using digital technologies to support the implementation of the circular economy. Further efforts are needed d to characterise such a relationship better. The present work conducts a systematic literature review aimed at understanding the nature and scope of the relationship by examining current knowledge at the intersection of the two domains, i.e. digital technologies and the circular economy. Specifically, the analysis focuses on identifying moderators and mediators of this relationship. About the former, the study discusses the relevance of management commitment, competencies, stakeholders and contextual factors; concerning the latter, the study discusses the relevance of supply chain integration and collaboration and examines in more detail the role of digital-enabled dynamic capabilities, given their promising relevance in the current debate. Based on the review, a research agenda is proposed with suggestions for future research directions on the relationship between digital technologies and the circular economy

Geoffroy de Lagasnerie, Logique de la création

Les universitaires ont raison d’être inquiets. La société ignore ce qu’ils sont et ce qu’ils font. Le journalisme véhicule les pires poncifs à leur sujet. Quant à leur institution, elle vient de traverser la pire crise de son histoire et ce n’est pas fini. Plusieurs électrochocs récents, souvent aux allures burlesques, ont secoué la vieille maison qui se voit poussée à la réflexivité : une blessure narcissique, suite à la publication en 2003 du classement dit de Shanghai qui reléguait les éta..

Risk perception and affective state on work exhaustion in obstetrics during the COVID-19 pandemic

Amulticenter cross-sectional survey study involving four Italian University Hospitals was performed to test the hypothesis that negative affect and positive affect (affective dimensions) mediate the association between risk perception (perceived risk of infection and death; cognitive dimensions) and the feeling of work exhaustion (WE) among obstetrics healthcare providers (HCPs) during the Coronavirus Disease 2019 (COVID-19) pandemic. Totally, 570 obstetrics HCPs were invited to complete the 104-item IPSICO survey in May 2020. A theoretical model built on the tested hypothesis was investigated by structural equation modelling. The model explained 32.2% of the WE variance. Only negative affect mediated the association between cognitive dimensions and WE and also the association between WE and psychological well-being before the pandemic, experiences of stressful events, female gender, and dysfunctional coping. Non-mediated associations withWE were observed for work perceived as a duty, experience of stressful events, support received by colleagues, and the shift strategy. Only previous psychological well-being, support by colleagues, and shift strategies were inversely associated with WE. Based on study results, monitoring negative than positive affect appears superior in predicting WE, with practical implications for planning psychological interventions in HCPs at the individual, interpersonal, and organizational levels

Diaphragm ultrasound evaluation during weaning from mechanical ventilation in COVID-19 patients: a pragmatic, cross-section, multicenter study

Background Diaphragmatic dysfunction is a major factor responsible for weaning failure in patients that underwent prolonged invasive mechanical ventilation for acute severe respiratory failure from COVID-19. This study hypothesizes that ultrasound measured diaphragmatic thickening fraction (DTF) could provide corroborating information for weaning COVID-19 patients from mechanical ventilation. Methods This was an observational, pragmatic, cross-section, multicenter study in 6 Italian intensive care units. DTF was assessed in COVID-19 patients undergoing weaning from mechanical ventilation from 1st March 2020 to 30th June 2021. Primary aim was to evaluate whether DTF is a predictive factor for weaning failure. Results Fifty-seven patients were enrolled, 25 patients failed spontaneous breathing trial (44%). Median length of invasive ventilation was 14 days (IQR 7-22). Median DTF within 24 h since the start of weaning was 28% (IQR 22-39%), RASS score (- 2 vs - 2; p = 0.031); Kelly-Matthay score (2 vs 1; p = 0.002); inspiratory oxygen fraction (0.45 vs 0.40; p = 0.033). PaO2/FiO(2) ratio was lower (176 vs 241; p = 0.032) and length of intensive care stay was longer (27 vs 16.5 days; p = 0.025) in patients who failed weaning. The generalized linear regression model did not select any variables that could predict weaning failure. DTF was correlated with pH (RR 1.56 x 10(27); p = 0.002); Kelly-Matthay score (RR 353; p < 0.001); RASS (RR 2.11; p = 0.003); PaO2/FiO(2) ratio (RR 1.03; p = 0.05); SAPS2 (RR 0.71; p = 0.005); hospital and ICU length of stay (RR 1.22 and 0.79, respectively; p < 0.001 and p = 0.004). Conclusions DTF in COVID-19 patients was not predictive of weaning failure from mechanical ventilation, and larger studies are needed to evaluate it in clinical practice further. Registered: ClinicalTrial.gov (NCT05019313, 24 August 2021)

Extragenital Müllerian adenosarcoma with pouch of Douglas location

Background: Of all female genital tract tumors, 1-3% are stromal malignancies. In 8-10% of cases, these are represented by Mullerian adenosarcoma an extremely rare tumor characterized by a stromal component of usually low-grade malignancy and by a benign glandular epithelial component. Variant that arises in the pouch of Douglas is scarcely mentioned in the medical literature.Case Presentation: A 49-year-old para-0 woman, was seen at our OB/GYN-UNIT because she complained vaguely of pelvic pain. She had a mass of undefined nature in the pouch of Douglas. A simple excision of the mass showed low-grade Mullerian adenosarcoma with areas of stromal overgrowth. One and a half year after surgery, at another hospital, a mass was detected in the patient's posterior vaginal fornix and removed surgically. Six months later she came back to our observation with vaginal bleeding and mass in the vaginal fornix. We performed radical surgery. The pathological examination showed recurrent adenosarcoma. Surgical treatment was supplemented by radiation therapy.Conclusions: The case of Mullerian adenosarcoma reported here is the third known so far in the literature that was located in the pouch of Douglas. To date, only two other such cases have been reported, including one resulting from neoplastic degeneration of an endometriotic cyst

Association between preoperative evaluation with lung ultrasound and outcome in frail elderly patients undergoing orthopedic surgery for hip fractures: study protocol for an Italian multicenter observational prospective study (LUSHIP)

Hip fracture is one of the most common orthopedic causes of hospital admission in frail elderly patients. Hip fracture fixation in this class of patients is considered a high-risk procedure. Preoperative physical examination, plasma natriuretic peptide levels (BNP, Pro-BNP), and cardiovascular scoring systems (ASA-PS, RCRI, NSQIP-MICA) have all been demonstrated to underestimate the risk of postoperative complications. We designed a prospective multicenter observational study to assess whether preoperative lung ultrasound examination can predict better postoperative events thanks to the additional information they provide in the form of "indirect" and "direct" cardiac and pulmonary lung ultrasound signs