The ecological rationality of decision criteria

Standard evolutionary game theory investigates the evolutionary fitness of alternative behaviors in a fixed and single decision problem. This paper instead focuses on decision criteria, rather than on simple behaviors, as the general behavioral rules under selection in the population: the evolutionary fitness of classic decision criteria for rational choice is analyzed through Monte Carlo simulations over various classes of decision problems. Overall, quantifying the uncertainty in a probabilistic way and maximizing expected utility turns out to be evolutionarily beneficial in general. Minimizing regret also finds some evolutionary justifications in our results, while maximin seems to be always disadvantaged by differential selection

Printed organic semiconductors for ionizing radiation detection

In the last years, Organic Field-Effect Transistors (OFETs) have shown a great potential in the field of X-rays direct detection, thanks to the possibility of fabricating flexible devices with low toxicity and cost-effective deposition processes. In this thesis, the composition of the active layer of OFETs based on an organic small molecule (TMTES) blended with an insulating polymer (polystyrene) was studied as a function of the ratio between the two components, of the molecular weight of the polymer and considering the effects of the addition of a Parylene-C encapsulation layer. The study of the TMTES:PS ratio confirmed the results of previous works reported in literature for different materials that indicated a lower amount of polystyrene as preferable, while the analysis of the role of polystyrene molecular weight showed no significant impact caused by the variation of this parameter. On the other hand, the addition of an encapsulating layer was associated with a higher sensitivity (S=(13.7±0.9)·103 µC·Gy-1cm-2) and with a tendency to retain the electrical parameters after electrical and radiative stress. These results open new possibilities to tune the features of blended materials as active layers of OFETs for ionizing radiation detection and to better understand the role and potential of the use of encapsulation layers in this kind of devices

News and misinformation consumption: A temporal comparison across European countries

The Internet and social media have transformed the information landscape, democratizing content access and production. While making information easily accessible, these platforms can also act as channels for spreading misinformation, posing crucial societal challenges. To address this, understanding news consumption patterns and unraveling the complexities of the online information environment are essential. Previous studies highlight polarization and misinformation in online discussions, but many focus on specific topics or contexts, often overlooking comprehensive cross-country and cross-topic analyses. However, the dynamics of debates, misinformation prevalence, and the efficacy of countermeasures are intrinsically tied to socio-cultural contexts. This work aims to bridge this gap by exploring information consumption patterns across four European countries over three years. Analyzing the Twitter activity of news outlets in France, Germany, Italy, and the UK, this study seeks to shed light on how topics of European significance resonate across these nations and the role played by misinformation sources. The results spotlight that while reliable sources predominantly shape the information landscape, unreliable content persists across all countries and topics. Though most users favor trustworthy sources, a small percentage predominantly consumes content from questionable sources, with even fewer maintaining a mixed information diet. The cross-country comparison unravels disparities in audience overlap among news sources, the prevalence of misinformation, and the proportion of users relying on questionable sources. Such distinctions surface not only across countries but also within various topics. These insights underscore the pressing need for tailored studies, crucial in designing targeted and effective countermeasures against misinformation and extreme polarization in the digital space

News and Misinformation Consumption in Europe: A Longitudinal Cross-Country Perspective

The Internet and social media have transformed news availability and accessibility, reshaping information consumption and production. However, they can also facilitate the rapid spread of misinformation, posing significant societal challenges. To combat misinformation effectively, it is crucial to understand the online information environment and news consumption patterns. Most existing research has primarily focused on single topics or individual countries, lacking cross-country comparisons. This study investigated information consumption in four European countries, analyzing three years of Twitter activity from news outlet accounts in France, Germany, Italy, and the UK and focusing on the role of misinformation sources. Our work offers a perspective on how topics of European significance are interpreted across various countries. Results indicate that reliable sources dominate the information landscape, although unreliable content is still present across all countries and topics. While most users engage with reliable sources, a small percentage consume questionable content. Interestingly, few users have a mixed information diet, bridging the gap between questionable and reliable news in the similarity network. Cross-country comparisons revealed differences in audience overlap of news sources, offering valuable guidance for policymakers and scholars in developing effective and tailored solutions to combat misinformation

Unveiling the hidden agenda: Biases in news reporting and consumption

Recognizing the presence and impact of news outlets’ biases on public discourse is a crucial challenge. Biased news significantly shapes how individuals perceive events, potentially jeopardizing public and individual well-being. In assessing news outlet reliability, the focus has predominantly centered on narrative bias, sidelining other biases such as selecting events favoring specific perspectives (selection bias). Leveraging machine learning techniques, we have compiled a six-year dataset of articles related to vaccines, categorizing them based on narrative and event types. Employing a Bayesian latent space model, we quantify both selection and narrative biases in news outlets. Results show third-party assessments align with narrative bias but struggle to identify selection bias accurately. Moreover, extreme and negative perspectives attract more attention, and consumption analysis unveils shared audiences among ideologically similar outlets, suggesting an echo chamber structure. Quantifying news outlets’ selection bias is crucial for ensuring a comprehensive representation of global events in online debates

The Limited Reach of Fake News on Twitter during 2019 European Elections

The advent of social media changed the way we consume content favoring a disintermediated access and production. This scenario has been matter of critical discussion about its impact on society. Magnified in the case of Arab Spring or heavily criticized in the Brexit and 2016 U.S. elections. In this work we explore information consumption on Twitter during the last European electoral campaign by analyzing the interaction patterns of official news sources, fake news sources, politicians, people from the showbiz and many others. We extensively explore interactions among different classes of accounts in the months preceding the last European elections, held between 23rd and 26th of May, 2019. We collected almost 400,000 tweets posted by 863 accounts having different roles in the public society. Through a thorough quantitative analysis we investigate the information flow among them, also exploiting geolocalized information. Accounts show the tendency to confine their interaction within the same class and the debate rarely crosses national borders. Moreover, we do not find any evidence of an organized network of accounts aimed at spreading disinformation. Instead, disinformation outlets are largely ignored by the other actors and hence play a peripheral role in online political discussions

The echo chamber effect on social media

Social media may limit the exposure to diverse perspectives and favor the formation of groups of like-minded users framing and reinforcing a shared narrative, that is, echo chambers. However, the interaction paradigms among users and feed algorithms greatly vary across social media platforms. This paper explores the key dif- ferences between the main social media platforms and how they are likely to influence information spreading and echo chambers’ formation. We perform a comparative analysis of more than 100 million pieces of content concerning several controversial topics (e.g., gun control, vaccination, abortion) from Gab, Facebook, Red- dit, and Twitter. We quantify echo chambers over social media by two main ingredients: 1) homophily in the interaction networks and 2) bias in the information diffusion toward like-minded peers. Our results show that the aggregation of users in homophilic clus- ters dominate online interactions on Facebook and Twitter. We conclude the paper by directly comparing news consumption on Facebook and Reddit, finding higher segregation on Facebook.Peer ReviewedPostprint (published version