50 research outputs found
How Does Twitter Account Moderation Work? Dynamics of Account Creation and Suspension During Major Geopolitical Events
Social media moderation policies are often at the center of public debate,
and their implementation and enactment are sometimes surrounded by a veil of
mystery. Unsurprisingly, due to limited platform transparency and data access,
relatively little research has been devoted to characterizing moderation
dynamics, especially in the context of controversial events and the platform
activity associated with them. Here, we study the dynamics of account creation
and suspension on Twitter during two global political events: Russia's invasion
of Ukraine and the 2022 French Presidential election. Leveraging a large-scale
dataset of 270M tweets shared by 16M users in multiple languages over several
months, we identify peaks of suspicious account creation and suspension, and we
characterize behaviours that more frequently lead to account suspension. We
show how large numbers of accounts get suspended within days from their
creation. Suspended accounts tend to mostly interact with legitimate users, as
opposed to other suspicious accounts, often making unwarranted and excessive
use of reply and mention features, and predominantly sharing spam and harmful
content. While we are only able to speculate about the specific causes leading
to a given account suspension, our findings shed light on patterns of platform
abuse and subsequent moderation during major events
Online Networks of Support in Distressed Environments: Solidarity and Mobilization during the Russian Invasion of Ukraine
Despite their drawbacks and unintended consequences, social media networks
have recently emerged as a crucial resource for individuals in distress,
particularly during times of crisis. These platforms serve as a means to seek
assistance and support, share reliable information, and appeal for action and
solidarity. In this paper, we examine the online networks of support during the
Russia-Ukraine conflict by analyzing four major social media networks- Twitter,
Facebook, Instagram, and YouTube. Using a large dataset of 68 million posts, we
explore the temporal patterns and interconnectedness between these platforms
and online support websites. Our analysis highlights the prevalence of
crowdsourcing and crowdfunding websites as the two main support platforms to
mobilize resources and solicit donations, revealing their purpose and contents,
and investigating different support-seeking and -receiving practices. Overall,
our study underscores the potential of social media in facilitating online
support in distressed environments through grassroots mobilization,
contributing to the growing body of research on the positive impact of online
platforms in promoting social good and protecting vulnerable populations during
times of crisis and conflict
Interference at the Single Photon Level Along Satellite-Ground Channels
Quantum interference arising from superposition of states is a striking
evidence of the validity of Quantum Mechanics, confirmed in many experiments
and also exploited in applications. However, as for any scientific theory,
Quantum Mechanics is valid within the limits in which it has been
experimentally verified. In order to extend such limits, it is necessary to
observe quantum interference in unexplored conditions such as moving terminals
at large distance in Space. Here we experimentally demonstrate single photon
interference at a ground station due to the coherent superposition of two
temporal modes reflected by a rapidly moving satellite thousand kilometers
away. The relative speed of the satellite induces a varying modulation in the
interference pattern. The measurement of the satellite distance in real time by
laser ranging allowed us to precisely predict the instantaneous value of the
interference phase. We then observed the interference patterns with visibility
up to with three different satellites and with path length up to 5000
km. Our results attest the viability of photon temporal modes for fundamental
tests of Physics and Quantum Communications in Space.Comment: Version accepted for publication in Phys. Rev. Let
Identifying and Characterizing Behavioral Classes of Radicalization within the QAnon Conspiracy on Twitter
Social media provide a fertile ground where conspiracy theories and radical ideas can flourish, reach broad audiences, and sometimes lead to hate or violence beyond the online world itself.
QAnon represents a notable example of a political conspiracy that started out on social media but turned mainstream, in part due to public endorsement by influential political figures. Nowadays, QAnon conspiracies often appear in the news, are part of political rhetoric, and are espoused by significant swaths of people in the United States. It is therefore crucial to understand how such a conspiracy took root online, and what led so many social media users to adopt its ideas. In this work, we propose a framework that exploits both social interaction and content signals to uncover evidence of user radicalization or support for QAnon. Leveraging a large dataset of 240M tweets collected in the run-up to the 2020 US Presidential election, we define and validate a multivariate metric of radicalization. We use that to separate users in distinct, naturally-emerging, classes of behaviors associated with radicalization processes, from self-declared QAnon supporters to hyper-active conspiracy promoters. We also analyze the impact of Twitter's moderation policies on the interactions among different classes: we discover aspects of moderation that succeed, yielding a substantial reduction in the endorsement received by hyperactive QAnon accounts. But we also uncover where moderation fails, showing how QAnon content amplifiers are not deterred or affected by the Twitter intervention. Our findings refine our understanding of online radicalization processes, reveal effective and ineffective aspects of moderation, and call for the need to further investigate the role social media play in the spread of conspiracies
Towards Quantum Communication from Global Navigation Satellite System
Satellite-based quantum communication is an invaluable resource for the
realization of a quantum network at the global scale. In this regard, the use
of satellites well beyond the low Earth orbits gives the advantage of long
communication time with a ground station. However, high-orbit satellites pose a
great technological challenge due to the high diffraction losses of the optical
channel, and the experimental investigation of such quantum channels is still
lacking. Here, we report on the first experimental exchange of single photons
from Global Navigation Satellite System at a slant distance of 20000
kilometers, by exploiting the retroreflector array mounted on GLONASS
satellites. We also observed the predicted temporal spread of the reflected
pulses due to the geometrical shape of array. Finally, we estimated the
requirements needed for an active source on a satellite, aiming towards quantum
communication from GNSS with state-of-the-art technology.Comment: Revte
Extending Wheeler's delayed-choice experiment to Space
Gedankenexperiments have consistently played a major role in the development
of quantum theory. A paradigmatic example is Wheeler's delayed-choice
experiment, a wave-particle duality test that cannot be fully understood using
only classical concepts. Here, we implement Wheeler's idea along a
satellite-ground interferometer which extends for thousands of kilometers in
Space. We exploit temporal and polarization degrees of freedom of photons
reflected by a fast moving satellite equipped with retro-reflecting mirrors. We
observed the complementary wave-like or particle-like behaviors at the ground
station by choosing the measurement apparatus while the photons are propagating
from the satellite to the ground. Our results confirm quantum mechanical
predictions, demonstrating the need of the dual wave-particle interpretation,
at this unprecedented scale. Our work paves the way for novel applications of
quantum mechanics in Space links involving multiple photon degrees of freedom.Comment: 4 figure
What are Your Pronouns? Examining Gender Pronoun Usage on Twitter
Stating your gender pronouns, along with your name, is becoming the new norm
of self-introductions at school, at the workplace, and online. The increasing
prevalence and awareness of nonconforming gender identities put discussions of
developing gender-inclusive language at the forefront. This work presents the
first empirical research on gender pronoun usage on large-scale social media.
Leveraging a Twitter dataset of over 2 billion tweets collected continuously
over two years, we find that the public declaration of gender pronouns is on
the rise, with most people declaring as using she series pronouns, followed by
he series pronouns, and a smaller but considerable amount of non-binary
pronouns. From analyzing Twitter posts and sharing activities, we can discern
users who use gender pronouns from those who do not and also distinguish users
of various gender identities. We further illustrate the relationship between
explicit forms of social network exposure to gender pronouns and their eventual
gender pronoun adoption. This work carries crucial implications for
gender-identity studies and initiates new research directions in gender-related
fairness and inclusion, as well as support against online harassment and
discrimination on social media.Comment: 23 pages, 11 figures, 2 table
Ethyl acetate extract from Cistus x incanus L. leaves enriched in myricetin and quercetin derivatives, inhibits inflammatory mediators and activates Nrf2/HO-1 pathway in LPS-stimulated RAW 264.7 macrophages.
Abstract
Cistus x incanus L. is a Mediterranean evergreen shrub used in folk medicine for the treatment of inflammatory disorders but the underlying mechanisms are not fully understood. We therefore investigated the anti-inflammatory effects of an ethyl acetate fraction (EAF) from C. x incanus L. leaves on lipopolysaccharide (LPS) activated RAW 264.7 macrophages. HPLC analysis revealed myricetin and quercetin derivatives to be the major compounds in EAF; EAF up to 1 µM of total phenolic content, was not cytotoxic and inhibited the mRNA expression of interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) (p < 0.05) and the production of prostaglandins E2 (PGE2) (p < 0.05). Meanwhile, EAF triggered the mRNA expression of interleukin-10 (IL-10) and elicited the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the expression of its main target gene, heme oxygenase-1 (HO-1) (p < 0.05). These data indicate that EAF attenuates experimental inflammation via the inhibition of proinflammatory mediators and at least in part, by the activation of Nrf2/HO-1 pathway. These effects are likely due to myricetin and quercetin derivatives but the role of other, less abundant components cannot be excluded. Further studies to confirm the relevance of our findings in animal models and to highlight the relative contribution of each component to the anti-inflammatory activity of EAF should be conducted