In recent years, political polarization saw a significant rise in many political systems. This revamped a scientific debate sparked decades ago, with different schools of thought debating on dynamics, factors, and causes of polarization itself. By looking at political elites\' polarizing strategy-one of the factors on which various theories seem to converge-this article tackles the question concerning the impact of the COVID-19 pandemic in terms of political communication. More specifically, we look at the case of a highly polarizing leader in Italy-Matteo Salvini, leader of Lega-in two campaigns held in 2020 before and after the first wave of the pandemic. By analyzing his messages on Facebook and Twitter, we build on the literature on the causes of affective polarization to study Salvini\'s use of partisan identity and divisive issues, also considering other crucial elements, such as the attacks against others, and followers\' engagement. The results highlight some changes between the two phases, but also a strong continuity in the polarizing strategy of Salvini\'s political communication.

We investigated how ideologically polarized civil society organizations (CSOs) in Turkey use Twitter. We analyzed tweets from 20 CSOs in Turkey for a period of 7 months by using the Information-Community-Action framework. For all types of CSOs, the number of information tweets was higher than the number of action tweets, which, in turn, was higher in number than the community tweets. Religious/conservative and anti-government CSOs posted significantly more tweets than secular and pro-government CSOs, respectively. Religious/conservative and pro-government CSOs posted more information and community tweets than secular and anti-government CSOs, respectively. The number of anti-government CSOs\' action tweets was higher than that of pro-government CSOs. We, therefore, propose that the ideological stance of a CSO is a factor affecting the content of its tweets in societies where CSOs are politically polarized.

We have designed, developed and evaluated an innovative portable magneto-optical detector (MOD) in which a light beam with variable polarization passes through a fluid sample immersed in a variable magnetic field. The light intensity is measured downstream along the forward scattering direction. The field is turned on and off through the in-and-out motion of nearby permanent magnets. As a result, for sufficiently magnetically and optically anisotropic samples, the optical absorption is sensitive to changes in the light polarization. Both detection and characterization applications are therefore available. For instance, both the degree of malaria infection can be measured and hemozoin crystalline properties can be studied. We present experimental results for synthetic hemozoin, and describe them in terms of the basic physics and chemistry underlying the correlations of the directions of the external magnetic field and the light beam polarization. We connect this work to a commercialized product for malaria detection and compare it to other magneto-optical instruments and methods. We conduct tests of absorption parameters, the electric polarizability tensor, and we discuss the connection to magnetic and electric dipole moments.

UNASSIGNED: Social media chatter in 2020 has been largely dominated by the COVID-19 pandemic. Existing research shows that COVID-19 discourse is highly politicized, with political preferences linked to beliefs and disbeliefs about the virus. As it happens with topics that become politicized, people may fall into echo chambers, which is the idea that one is only presented with information they already agree with, thereby reinforcing one\'s confirmation bias. Understanding the relationship between information dissemination and political preference is crucial for effective public health communication.
UNASSIGNED: We aimed to study the extent of polarization and examine the structure of echo chambers related to COVID-19 discourse on Twitter in the United States.
UNASSIGNED: First, we presented Retweet-BERT, a scalable and highly accurate model for estimating user polarity by leveraging language features and network structures. Then, by analyzing the user polarity predicted by Retweet-BERT, we provided new insights into the characterization of partisan users.
UNASSIGNED: We observed that right-leaning users were noticeably more vocal and active in the production and consumption of COVID-19 information. We also found that most of the highly influential users were partisan, which may contribute to further polarization. Importantly, while echo chambers exist in both the right- and left-leaning communities, the right-leaning community was by far more densely connected within their echo chamber and isolated from the rest.
UNASSIGNED: We provided empirical evidence that political echo chambers are prevalent, especially in the right-leaning community, which can exacerbate the exposure to information in line with pre-existing users\' views. Our findings have broader implications in developing effective public health campaigns and promoting the circulation of factual information online.

We present the current status of development of our code for performing Molecular Dynamics (MD) simulations exploiting a polarizable force field based on the Fluctuating Charge (FQ) method and non-Periodic Boundary Conditions (NPBC). Continuing on the path set in a previous work, we increased the capabilities of the code by implementing a number of new features, including: a non-iterative algorithm for rigid trigonal molecule simulations; two additional temperature coupling schemes; a meta-dynamics based approach for effective free energy evaluations. Although these are well known algorithms, each present in one or more widely used MD packages, they have now been tested, for the first time, in the context of the FQ model coupled with NPBC. As case studies, we considered three aqueous ions of increasing charge, namely Na+, Ca2+ and La3+, at infinite dilution. In particular, by exploiting a computational approach recently proposed by our group and based on the metadynamics technique, we focused on the important role played by solvent polarization on ionic hydration structures, also investigating the free energy landscapes of ion coordination and the water exchange rates. Such an approach, previously tested with standard non-polarizable models, was applied here to evaluate the effects of explicit polarization on water exchange barriers between different solvent coordination structures. Moreover, we have analyzed and discussed in some detail non-linear electrostatic effects arising from solvent polarization while going from a mono- to a di- and trivalent ion.