Polarization Dynamics Research Articles

Structural, optical, dielectric, and ferroelectric properties in [formula omitted] ceramics prepared by a solvothermal reflux approach

Chromium (Cr3+) doped BaTi1−xCrxO3 (x = 0.0, 0.03, 0.06, and 0.09) ceramics were prepared by the solvothermal reflux approach. X-ray diffraction analysis confirmed the development of tetragonal structures with P4mm symmetry in the prepared samples. The SEM analysis showed that Cr3+ doping resulted in a microstructure that was dense, uniform, and had smaller grains. Surface chemical information and oxidation states were studied using X-ray photoelectron spectroscopy. The diffuse reflectance spectrum confirmed the effect of Cr3+ content on the direct optical bandgap of BaTi1−xCrxO3 samples which shifts from 3.21 eV to 2.73 eV with increasing Cr3+ content. Dielectric permittivity was found to increase in the low-frequency region with increasing Cr3+ doping content up to x = 0.06, while it decreased in the high-frequency region compared to an undoped sample. The observed behavior of permittivity might be explained in terms of the formation of oxygen vacancy defects and their effects on the polarization dynamics of the material. Moreover, the addition of Cr3+ doping had a strong effect on the ferroelectric characteristics, as seen by the formation of a pinched hysteresis loop, resulting in the improvement of energy storage properties. Based on the obtained results, the sample with x = 0.06 exhibited an enhancement of about 3.3 times in energy discharge density and 26 % in storage efficiency compared to the undoped sample. This might be due to a large difference between the values of maximum and remnant polarizations, reduced tangent loss, and a smaller grain size, which makes this material attractive for use in energy storage devices.

Shift in Public Opinion Formations on Defense, Energy, and Migration: The Case of Russia’s War Against Ukraine

Abstract Russia’s war on Ukraine came as a shock to the Western world. In this context, the study of public opinion change is crucial for understanding the dynamics of political attitudes and societal polarization. Using Germany as an exemplary case study, we investigate how public opinion changed regarding defense, energy supply, and migration as three crucial policy domains in the first year of the war. Using a representative eight-wave online panel survey study, we map attitudes in the general population and among supporters of different parties, tracing their development over time. Our analyses lead to two key insights: First, attitudes toward defense, energy supply, and migration remained remarkably stable over time. Second, we found a high degree of consensus across the partisan spectrum. Only the supporters of the far-right populist party systematically diverged from the general population, and this discrepancy grew larger over time. Our findings contribute significantly to the understanding of political attitude formation and processes of social polarization along cleavages in times of abrupt societal change.

Democracy and the Epistemic Problems of Political Polarization

Political polarization is one of the most discussed challenges facing contemporary democracies and is often associated with a broader epistemic crisis. While inspiring a large literature in political science, polarization’s epistemic problems also have significance for normative democratic theory, and this study develops a new approach aimed at understanding them. In contrast to prominent accounts from political psychology—group polarization theory and cultural cognition theory—which argue that polarization leads individuals to form unreliable political beliefs, this study focuses on system-level diversity. It argues that polarization’s epistemic harms are best located in its tendency to reduce the diversity of perspectives utilized in a democratic system and in how this weakens the system’s ability to identify and address problems of public concern. Understanding such harms is also argued to require a greater consideration of the political dynamics of polarization and issues of elite discourse, alongside political psychology.

Charge-Transfer-Controlled Quantum Dynamics of HCl Dissociation on the Ag/Au(111) Bimetallic Alloy Surface.

Understanding polar molecule dynamics on bimetallic surfaces, especially electropositivity and electronegativity, remains a challenge. Here, we report the reactivity of HCl on a strained Ag monolayer on Au(111) using six-dimensional quantum dynamics with a new machine-learning-based potential energy surface. Surprisingly, HCl reactivity is significantly suppressed by the Ag-Au interaction despite a lower HCl+Ag/Au(111) barrier than pure Ag(111). This arises from charge transfer between Ag and Au, where electronegative Au makes the top Ag layer on Ag/Au(111) electropositive, unlike that on pure Ag(111). Electropositive Ag in HCl+Ag/Au(111) attracts Cl, yielding an unfavorable H-Cl configuration and reduced reactivity. These findings deepen our understanding of polar molecule interactions on bimetallic surfaces, highlighting the role of charge transfer in dissociative chemisorption and the implications for catalyst design in heterogeneous catalysis.

The diffusion of digital skills across EU regions: structural drivers and polarisation dynamics

ABSTRACT The digital transformation is an important driver of long-run productivity growth and, as such, it has the potential to promote a more inclusive and sustainable growth. However, digital capabilities, crucial to develop and govern new digital technologies, are unevenly distributed across European regions, increasing the risk of divergence and polarisation. By taking advantage of a set of original indicators capturing the level of digital skills in the regional workforce, this work analyses the factors shaping the process of digital skill accumulation in the EU over the period 2011–2018. Relying on transition probability matrices and dynamic random effects probit models, we provide evidence of a strong and persistent regional polarisation in the adoption and deployment of digital skills. Further, we investigate whether structural factors and European funds (European Regional Development Fund, Cohesion Funds and European Social Funds) are capable of shaping the digitalisation process and favouring regional convergence.

Suppression of polarization instability in ultrashort Fabry–Pérot fiber laser

Due to the weak birefringence from the intracavity fiber, vector solitons are easily generated in GHz-fundamental-repetition-rate mode-locked fiber lasers, which can exhibit diverse time-varying polarization dynamics. These soliton dynamics can lead to polarization instability of the pulse train, which prevents industrial and scientific applications that require stable and uniform pulse trains. However, it is hard to suppress the polarization instability due to insufficient space for inserting traditional polarizers and difficulties in enhancing the fiber birefringence in the ultrashort fiber laser cavity. To this end, here we propose an alternative method that can effectively transform the vector solitons into scalar solitons by exploring gold nanorod (GNR) film as a polarizer in the laser cavity. First, the theoretical studies of polarization dynamics in ultrashort Fabry–Pérot (FP) fiber lasers with and without intracavity GNR film are conducted. The results indicate that the use of GNR film can significantly suppress the polarization instability and generate scalar solitons. Then, the large-scale preparation of GNRs with longitudinal surface plasmon resonance absorption peak of >1380 nm is realized by a two-step seed-mediated method, and the GNR film with an operation wavelength range covering the C + L band is fabricated by electrospinning. Finally, we apply the GNR film to a 2-cm-long FP fiber laser, and convert polarization rotation vector solitons to linearly polarized solitons (LPSs) at 1.5 μm. The polarization extinction ratio of the improved LPS pulse train is up to 33 dB.

Charting the Impacts of Media Discourses on the European Integration Project

The over-exposure to information facilitated by the hybrid media system and social networks is a key factor contributing to the increasing polarization of public opinion on major political issues. The European integration project is one of the major political processes affected by information manipulation and disinformation. In this regard, social networks have become powerful tools for nurturing news siloes or “echo chambers,” influencing people’s perceptions of important political issues in a manner that could have a destabilizing effect on democratic processes and institutions. In this context, the role of media discourses and their circulation among networked publics has become particularly relevant, leading audiences to adopt different views supporting or rejecting the European project. This thematic issue features a range of articles considering how the Europeanization process is impacted by discourses circulating in the hybrid media system or threatened by the destructive dynamics of disinformation and polarization.

Soliton polarization dynamics in a fiber laser of zero dispersion.

Polarization properties of a soliton generated in a fiber laser of zero dispersion are investigated. Similar to the solitons generated in a fiber laser of all anomalous dispersion, the polarization ellipse of the soliton rotated during pulse evolution inside the cavity. The number of rotations relies on the cavity averaged birefringence with nonlinear bias. The larger the cavity averaged birefringence is, the bigger the bias is. When the period multiplying of solitons appears, the number of rotations depends on both multiplying periods and the cavity averaged birefringence. Multiple polarization states can be observed at a fixed position in the cavity depending on the multiplying period. When the cavity length is equal to n times of the averaged beat length, the polarization ellipse of the soliton rotates n∗m times at a fixed position, where m is equal to the multiplying period.

Efficient polarization redistribution in hyperpolarized 1-D-propane produced via pairwise parahydrogen addition

Parahydrogen-Induced Polarization (PHIP) is NMR hyperpolarization technique that has matured from fundamental science to a biomedical tool for production of hyperpolarized MRI contrast agents. The spin order of nascent parahydrogen-derived protons can be employed directly for enhancement of their NMR signals or for polarization transfer to other nuclei in the hydrogenation product. In this work, we study the process of pairwise parahydrogen addition to propylene, which results in symmetric propane molecule with substantially enhanced methyl and methylene NMR signals. Specifically, we have synthesized site-selectively isotopically labeled 3-d-propylene molecule to study polarization dynamics in the resulting monodeuterated propane after pairwise parahydrogen addition. The deuterium presence in the hyperpolarized propane product results in a minute isotope chemical shift effect allowing to distinguish the proton resonances of CH3 and CH2D groups at 600 MHz. Pairwise parahydrogen 1,2-addition to 3-d-propylene was first confirmed by performing the reaction inside a 600 MHz NMR spectrometer, i.e., in the weakly-coupled regime at 14 T, where proton polarization dynamics is restricted to the molecular sites of parahydrogen addition. However, when the pairwise parahydrogen addition is performed in the strongly-coupled regime, i.e., at the Earth's magnetic field, efficient polarization transfer to CH2D protons is readily observed, leading to polarization redistribution between the three inequivalent sites. This finding is important as it sheds light on polarization dynamics in the strongly coupled symmetric spin systems such as propane studied here—the presented results are expected to be applicable to other spin systems such as butane.

Bidynamical all-optical reservoir computing for parallel task processing.

A bidynamical all-optical reservoir computing (RC) system for parallel task processing is proposed based on a unidirectional semiconductor optical amplifier optical fiber loop. The polarization dynamics and intensity dynamics are excited by the input signals injected into the reservoir via phase modulation and intensity modulation, respectively. Simultaneous computation of two independent tasks is implemented based on the dynamical responses in polarization and intensity of the optical fiber loop. To our knowledge, this is the first time that two kinds of dynamical responses of an all-optical RC system are used as independent task processing channels to implement parallel task processing. The proposed RC system can achieve good parallel task processing performance with low system cost.

Emulating lateral gravity wave propagation in a global chemistry–climate model (EMAC v2.55.2) through horizontal flux redistribution

Abstract. The columnar approach of gravity wave (GW) parameterisations in weather and climate models has been identified as a potential reason for dynamical biases in middle-atmospheric dynamics. For example, GW momentum flux (GWMF) discrepancies between models and observations at 60∘ S arising through the lack of horizontal orographic GW propagation are suspected to cause deficiencies in representing the Antarctic polar vortex. However, due to the decomposition of the model domains onto different computing tasks for parallelisation, communication between horizontal grid boxes is computationally extremely expensive, making horizontal propagation of GWs unfeasible for global chemistry–climate simulations. To overcome this issue, we present a simplified solution to approximate horizontal GW propagation through redistribution of the GWMF at one single altitude by means of tailor-made redistribution maps. To generate the global redistribution maps averaged for each grid box, we use a parameterisation describing orography as a set of mountain ridges with specified location, orientation and height combined with a ray-tracing model describing lateral propagation of so-generated mountain waves. In the global chemistry–climate model (CCM) EMAC (ECHAM MESSy Atmospheric Chemistry), these maps then allow us to redistribute the GW momentum flux horizontally at one level, obtaining an affordable overhead of computing resources. The results of our simulations show GWMF and drag patterns that are horizontally more spread out than with the purely columnar approach; GWs are now also present above the ocean and regions without mountains. In this paper, we provide a detailed description of how the redistribution maps are computed and how the GWMF redistribution is implemented in the CCM. Moreover, an analysis shows why 15 km is the ideal altitude for the redistribution. First results with the redistributed orographic GWMF provide clear evidence that the redistributed GW drag in the Southern Hemisphere has the potential to modify and improve Antarctic polar vortex dynamics, thereby paving the way for enhanced credibility of CCM simulations and projections of polar stratospheric ozone.

Modeling opinion polarization on social media: Application to Covid-19 vaccination hesitancy in Italy.

The SARS-CoV-2 pandemic reminded us how vaccination can be a divisive topic on which the public conversation is permeated by misleading claims, and thoughts tend to polarize, especially on online social networks. In this work, motivated by recent natural language processing techniques to systematically extract and quantify opinions from text messages, we present a differential framework for bivariate opinion formation dynamics that is coupled with a compartmental model for fake news dissemination. Thanks to a mean-field analysis we demonstrate that the resulting Fokker-Planck system permits to reproduce bimodal distributions of opinions as observed in polarization dynamics. The model is then applied to sentiment analysis data from social media platforms in Italy, in order to analyze the evolution of opinions about Covid-19 vaccination. We show through numerical simulations that the model is capable to describe correctly the formation of the bimodal opinion structure observed in the vaccine-hesitant dataset, which is witness of the known polarization effects that happen within closed online communities.

Arctic Polar Vortex Dynamics According to the Delineation Method Using Geopotential

Arctic Polar Vortex Dynamics According to the Delineation Method Using Geopotential

Derivative of aminoresin as potent anti-virulence agent: Synthesis, spectral (FT-IR, UV, NMR) analysis, molecular docking, effect of polar solvation dynamics, and quantum chemical investigation

This work undertakes a comprehensive study encompassing the synthesis, spectral characterization (FT-IR, UV, 1HNMR , 13CNMR), exploration of polar solvation dynamics (DMSO, EtOH, MeOH) on the molecular structure, quantum chemical calculations, topological (ELF, NCI) analysis, and molecular docking investigation. The focal point is a derivative of amino terpolymer resin, synthesized via the condensation of 4,4′-diaminodiphenylmethane, 8-hydroxyquinoline, and formaldehyde (DHQF). Thorough examination of the compound was conducted to evaluate its responsiveness in varying solvents and investigate its viability as a key candidate for antivirulent therapy against toxins from Vibrio cholerae and Salmonella enterica. Simulation of solvation dynamics underscored the compound's robust thermodynamic stability even at lower temperatures. Primary vibrations noted within the compound encompassed CH, OH, NH, CH2, and CN vibrations, whereas UV spectroscopy unveiled an electronic shift from HOMO to LUMO, featuring peak absorption at 292.77 nm, influenced by its interaction with DMSO. The molecular docking analysis reveals the terpolymer's significant bioactivity against proteins 7EE6 (affinity: −6.7 kcal/mol) and 5V6f (affinity: -7.1 kcal/mol) associated with V. cholerae and S. enterica. The binding affinity of DHQF with S. enterica toxin protein (PDB: 7EE6) is comparable to that of standard drug Ciprofloxacin (affinity: −6.9 kcal/mol) and the toxin protein. However, the binding affinity between DHQF and V. cholerae toxin protein 5V5F considerably surpasses the binding affinity (−4.6 kcal/mol) between Doxycycline and the toxin protein. More so, the complex shows close binding affinities to both proteins and a higher number of conventional hydrogen bonds, this formed multiple favorable interactions, particularly conventional hydrogen bonds, contributing significantly to the stability of the ligand-protein complexes. In conclusion, the analyzed terpolymer displayed favorable qualities and interactions, which establish it as a strong candidate for addressing the targeted V. cholerae and S. enterica pathogens. These findings highlight the compound's impressive stability and its potential for various therapeutic applications in different areas.

Ergodic polar cluster state and its dynamics in K and Nb modified BaTiO3

Ferroelectric to relaxor crossover of (KxBa1-x)(NbxTi1-x)O3 [KBNTx]; (x = 0, 0.05, 0.075 and 0.150) system has been investigated by exploring its average and local structure using X-ray diffraction, Raman scattering and dielectric spectroscopy. X-ray diffraction confirmed all compositions' overall cubic (Pm-3m) structure. Dielectric spectroscopy clearly showed ferroelectric to relaxor crossover at x = 0.150. In the Raman spectra of doped compounds, three new modes of chemical origin that are absent in BaTiO3 are observed at frequencies ∼120 cm−1, 830 cm−1 and 850 cm−1 at room temperature. The temperature-dependent Raman scattering revealed the existence of ergodic polar regions by the presence of first-order ferroelectric mode at 302 cm−1 [B1/E(TO3)/E(LO2)], along with two static disorder-related modes 220 and 550 cm−1 for T > Tc in the paraelectric phase. Moreover, Raman studies also elucidate that the decreased size of ergodic polar regions is responsible for relaxor crossover at x = 0.150 composition with the increased broadening of 302 cm−1 modes with an increase of K and Nb concentration. Further, the polar dynamic investigations indicated that the interactions among polar nano regions slow down nano-polar dynamics without freezing or glass transition. Identifying polar regions and their dynamics in the present work will significantly impact the understanding of the tunability of K and Nb-modified BaTiO3 lead-free ferroelectrics.

Apical polarity and actomyosin dynamics control Kibra subcellular localization and function in Drosophila Hippo signaling

The Hippo pathway is an evolutionarily conserved regulator of tissue growth that integrates inputs from both polarity and actomyosin networks. An upstream activator of the Hippo pathway, Kibra, localizes at the junctional and medial regions of the apical cortex in epithelial cells, and medial accumulation promotes Kibra activity. Here, we demonstrate that cortical Kibra distribution is controlled by a tug-of-war between apical polarity and actomyosin dynamics. We show that while the apical polarity network, in part via atypical protein kinase C (aPKC), tethers Kibra at the junctional cortex to silence its activity, medial actomyosin flows promote Kibra-mediated Hippo complex formation at the medial cortex, thereby activating the Hippo pathway. This study provides a mechanistic understanding of the relationship between the Hippo pathway, polarity, and actomyosin cytoskeleton, and it offers novel insights into how fundamental features of epithelial tissue architecture can serve as inputs into signaling cascades that control tissue growth, patterning, and morphogenesis.

Transformation of internet addiction on the background of social isolation and security crisis

Aim — based on the analysis of the characteristics of Internet addiction, identify its peculiarities on the background of social isolation and security crisis. Materials and methods. The study was conducted on a contingent of 120 respondents (students of higher education) aged 18 to 23, who have experience of permanent stay in conditions of social isolation in Ukraine (2020—2023), with established Internet-addiction according to Internet Addiction Test (K. Young, 1998) and Internet Use Disorders Identification Test (Linskiy I. V., Minko A. I., Artemchuk A. P. et al., 2009). The distribution of the contingent by gender was symmetrical. The research method is a structured psychological interview. Study results. In our analysis, it becomes evident that the excessive utilization of the Internet does not merely align with a series of non-chemical addictions; rather, it operates as a facilitative mechanism for a broad range of behavioral and psychological transgressions, which arise as an interconnected functional entity. Within this multifaceted spectrum, we discern two discrete categories: the formation of compulsive behavior patterns and the justification of pre-existing behavior abnormalities. Compulsive behavior patterns include compulsive gaming and gambling behavior, compulsive social media use, compulsive pornography consumption, news-related compulsive behavior. Formation of compulsive behavior patterns associated with problematic excessive use of Internet have such mechanisms: openness and accessibility of hyper-stimulating content, reinforcement and rewards with feedback loops, social comparison, escapism and avoidance, information overload. Justification of pre-existing behavior abnormalities associated with problematic excessive use of Internet include reinforcement of attention-seeking and provocative behaviors; reinforcement of rude and violent behaviors, reinforcement of self-harm and destructive behaviors, progressive reinforcement of deviant sexuality, reinforcement of cult-like behavior. Noticed underlying mechanisms: echo chambers, disinhibition due to anonymity, group polarization and competitive dynamics. Conclusions. Behavioral and psychological disorders linked to problematic excessive Internet use do not fit neatly into a singular pathological disorder classification within current assessment frameworks that may trivialize Internet addiction as a mere form of non-chemical addiction. Instead, in the contemporary context, it is imperative to examine and thoroughly evaluate the intricate array of behavioral and psychological disorders that manifest through Internet usage. Key words: Internet, addiction, Internet addiction, compulsions, behavior violations

Phase stability diagram, self-similar structures, and multistability in a free-running VCSEL with a small misalignment between the phase and amplitude anisotropies.

We report on the global dynamics of a free-running vertical-cavity surface-emitting laser (VCSEL) with misalignment between the linear phase and amplitude anisotropies due to the fact that this case might occur in practice caused unintentionally by minor manufacturing variations or design, in virtue of high-resolution phase stability diagrams, where two kinds of self-similar structures are revealed. Of interest is that the Arnold tongue cascades covered by multiple distinct periodicities are discovered for the first time in several scenarios specified in the free-running VCSEL, to the best of our knowledge. Additionally, we also uncover the existence of multistability through the basin of the attraction, as well as the eyes of anti-chaos and periodicity characterized by fractal. The findings may shed new light on interesting polarization dynamics of VCSELs, and also open the possibility to detect the above-mentioned structures experimentally and develop some potential applications.

De-sounding echo chambers: Simulation-based analysis of polarization dynamics in social networks

As online social networks have become dominant platforms for public discourse worldwide, there is growing anecdotal evidence of a concurrent rise in social antagonisms. Yet, while the increase in polarization is evident, the extent to which these digital communication ecosystems are driving this shift remains elusive. A dominant scholarly perspective suggests that digital social media lead to the compartmentalization of information channels, potentially culminating in the emergence of echo chambers. However, a growing body of empirical research suggests that the mechanisms influencing ideological demarcation are more complex than a complete communicative decoupling of user groups. This study introduces two intertwined principles that elucidate the dynamics of digital communication: First, socio-cognitive biases of social group formation enforce internal congruence of ideological communities by demarcation from outsiders. Second, algorithmic personalization of content contributes to ideological network formation by creating social redundancy, wherein the same individuals frequently interact in various roles, such as authors, recipients, or disseminators of messages, leading to a surplus of shared ideological fragments. Leveraging these insights, we pioneer a computational simulation model, integrating machine learning based on behavioral data and established recommendation technologies, to explore the evolution of social network structures in digital exchanges. Utilizing advanced methods in opinion dynamics, our model uniquely captures both the algorithmic delivery and the subsequent dissemination of messages by users. Our findings reveal that in ambiguous debate scenarios, the dual components of our model are essential to accurately capture the emergence of social polarization. Consequently, our model offers a forward-looking perspective on the evolution of network communication, facilitating nuanced comparisons with empirical graph benchmarks.

Polarization Dynamics of Narrow Spectral Modes of a Random Distributed Feedback Raman Fiber Laser

Polarization Dynamics of Narrow Spectral Modes of a Random Distributed Feedback Raman Fiber Laser