Polarization Dynamics Research Articles

Cleavage politics, polarisation and participation in Western Europe

Polarisation over cultural issues and the emergence of radical, often populist, challenger parties indicate a fundamental restructuring of political conflict in Western Europe. The emerging divide crosscuts and, in part, reshapes older cleavages. This special issue introduction highlights how the transformation of cleavage structures relates to the dynamics of polarisation and political participation. The contributions to the special issue innovate in two ways. First, they adapt concepts and measures of ideological and affective polarisation to the context of Europe’s multi-party and multi-dimensional party competition. Second, they emphasise electoral and protest politics, examining how ideological and affective polarisation shape electoral and non-electoral participation. Apart from introducing the contributions, the introduction combines different datasets – the Chapel Hill Expert Survey, Comparative Study of Electoral Systems and the European Social Survey – to sketch an empirical picture of differentiated polarisation with types of polarisation only weakly associated cross-arena, cross-nationally and over time.

HIIT Ameliorates Inflammation and Lipid Metabolism by Regulating Macrophage Polarization and Mitochondrial Dynamics in the Liver of Type 2 Diabetes Mellitus Mice.

High-intensity interval training (HIIT), a new type of exercise, can effectively prevent the progression of metabolic diseases. The aim of this study was to investigate the effects of HIIT on liver inflammation and metabolic disorders in type 2 diabetes mellitus (T2DM) mice induced by a high-fat diet (HFD) combined with streptozotocin (STZ) and to explore the possible mechanisms of macrophage polarization and mitochondrial dynamics. Our results showed that HIIT can increase fatty acid oxidation-related gene (PPARα, CPT1α, and ACOX1) mRNA levels and decrease adipogenesis-related gene (PPARγ) mRNA levels to improve liver metabolism in T2DM mice. The improvement of lipid metabolism disorder may occur through increasing liver mitochondrial biosynthesis-related genes (PGC-1α and TFAM) and restoring mitochondrial dynamics-related gene (MFN2 and DRP1) mRNA levels. HIIT can also reduce the mRNA levels of liver inflammatory factors (TNF-α, IL-6, and MCP-1) in T2DM mice. The reduction in liver inflammation may occur through reducing the expression of total macrophage marker (F4/80) and M1 macrophage marker (CD86) mRNA and protein and increasing the expression of M2 macrophage marker (CD163, CD206, and Arg1) mRNA and protein in the liver. HIIT can also increase the expression of insulin signaling pathway (IRS1, PI3K, and AKT) mRNA and protein in the liver of T2DM mice, which may be related to the improvements in liver inflammation and lipid metabolism. In conclusion, these results suggested that 8 weeks of HIIT can improve inflammation and lipid metabolism disorders in the liver of type 2 diabetes mellitus mice, macrophage M1/M2 polarization, and mitochondrial dynamics may be involved in this process.

Identification of internal polarization dynamics for solid oxide fuel cells investigated by electrochemical impedance spectroscopy and distribution of relaxation times

Reliability and durability are two major problems restricting for Solid oxide fuel cells (SOFCs) industrial applications. To ensure the long-term stability, understood the internal operation mechanism of SOFC was necessary. The polarization curve combined with the distribution of relaxation times (DRT) method to analyze the electrochemical impedance spectroscopy (EIS) was used to identify the SOFCs modulation and degradation effect through the excitation frequency. Dynamic evolution of carbon deposition process and specific time constants were determined employing EIS and DRT. Special attention was paid to the dependency between the complex reaction processes that occur during the different operation of SOFC. The corresponding frequencies of concentration and activation polarization resistances in EIS were investigated under various gas compositions. The high concentration polarization resistance caused by the addition of nitrogen and hydrogen starvation was the key limiting factor for high cell power density. The total polarization resistance increased from 1.50 Ω/cm2 to 5.26 Ω/cm2 when the H2:N2 ratio decreased from 1:0 to 1:5. The anode did not deteriorate due to the poisoning of Ni particles in a short-term tested under 0.5 A/cm2 current density when the fuel was methane.

Single-shot measurement of wavelength-resolved state of polarization dynamics in ultrafast lasers using dispersed division-of-amplitude

Characterization of the state of polarization (SOP) of ultrafast laser emission is relevant in several application fields such as field manipulation, pulse shaping, testing of sample characteristics, and biomedical imaging. Nevertheless, since high-speed detection and wavelength-resolved measurements cannot be simultaneously achieved by commercial polarization analyzers, single-shot measurements of the wavelength-resolved SOP of ultrafast laser pulses have rarely been reported. Here, we propose a method for single-shot, wavelength-resolved SOP measurements that exploits the method of division-of-amplitude under far-field transformation. A large accumulated chromatic dispersion is utilized to time-stretch the laser pulses via dispersive Fourier transform, so that spectral information is mapped into a temporal waveform. By calibrating our test matrix with different wavelengths, wavelength-resolved SOP measurements are achieved, based on the division-of-amplitude approach, combined with high-speed opto-electronic processing. As a proof-of-concept demonstration, we reveal the complex wavelength-dependent SOP dynamics in the build-up of dissipative solitons. The experimental results show that the dissipative soliton exhibits far more complex wavelength-related polarization dynamics, which are not shown in single-shot spectrum measurement. Our method paves the way for single-shot measurement and intelligent control of ultrafast lasers with wavelength-resolved SOP structures, which could promote further investigations of polarization-related optical signal processing techniques, such as pulse shaping and hyperspectral polarization imaging.

Polarization dynamics of a vertical external-cavity surface-emitting laser with a saturable absorber mirror.

We investigate experimentally the polarization dynamics of a vertical external-cavity surface-emitting laser with a saturable absorber mirror in the cavity. We demonstrate that the normalized Stokes parameters and degree of polarization are functions of time reaching extreme values around the pulse peaks. Our experiments show that light is elliptically polarized, being able to have a circular right-handed or left-handed component, depending on the orientation of the saturable absorber mirror.

Dynamics of Polarization: Affective Partisanship and Policy Divergence

AbstractWe explore the dynamics of affective partisanship and policy divergence in a behavioral voting model. Voters are adaptive and influenced by partisan affect, while political parties are rational and office motivated. We show that the affective partisanship of the electorate and the divergence of party platforms can be mutually reinforcing, thus providing an explanation for the observed co-movement of affective and elite polarization in recent decades. Whether the induced behavioral path exhibits low polarization or high polarization depends on the salience of group identity and the number of moderate voters. Thus, shocks to those factors, perhaps due to such events as economic crises or war, can lead to the polarization or depolarization of the electorate and of the elite.

Complex nonlinear dynamics of polarization and transverse modes in a broad-area VCSEL

Lasers can exhibit nonlinear and chaotic dynamics driven by the interaction of multiple lasing modes, and investigating the different scenarios of mode competition and bifurcations of their dynamics is of great interest on a fundamental level as well as in view of applications. We study the dynamics of a broad-area vertical-cavity surface-emitting laser (VCSEL) in solitary continuous-wave operation with a comprehensive investigation of its polarization state, lasing spectra, near-field distributions, and temporal dynamics. Fluctuations at the frequency of birefringence splitting and other frequency components develop in a series of bifurcations. The bifurcations coincide with changes of the transverse lasing modes and/or the polarization state, demonstrating the importance of both the spatial and polarization degrees of freedom for mode competition. As a consequence, the inherent nonlinear dynamics of broad-area VCSELs is significantly more complex than the dynamics of VCSELs with a single spatial mode.

A Microfluidic Model of AQP4 Polarization Dynamics and Fluid Transport in the Healthy and Inflamed Human Brain: The First Step Towards Glymphatics‐on‐a‐Chip (Adv. Biology 12/2022)

A Microfluidic Model of AQP4 Polarization Dynamics and Fluid Transport in the Healthy and Inflamed Human Brain: The First Step Towards Glymphatics‐on‐a‐Chip (Adv. Biology 12/2022)

Fast electron and slow hole spin relaxation in CsPbI3 nanocrystals

Spin-dependent properties of lead halide perovskites (LHPs) have recently gained significant attention paving their way toward spin-optoelectronic applications. However, separate measurements of the electron and hole spin relaxation rates are so far missing in LHPs. The knowledge of the electron and hole spin relaxation timescales is necessary to understand the spin-dependent properties of LHPs. Here, we report on the spin polarization dynamics in CsPbI3 nanocrystals (NCs). We employ polarization dependent ultrafast differential transmission spectroscopy (DTS) at room temperature to study the spin polarization dynamics in this system. In the case of pure CsPbI3 NCs, it is not possible to measure separately electron and hole spin relaxation rates from the polarization dependent DTS. Here, we introduce the soluble fullerene derivative PC60BM as an electron acceptor along with CsPbI3 to create an imbalance between the photoexcited electrons and holes in the NCs and, thus, affecting their spin-dependent carrier distribution. CsPbI3:PC60BM blend sample shows a distinct difference in the spin dependent kinetics of the DTS spectra as compared to the NCs-only sample. With the help of a kinetic model for the spin-dependent charge carrier distributions, we separately determine the electron and hole spin relaxation times in CsPbI3 NCs. We find that the room temperature hole spin lifetime (τh ∼ 5 ps) is ∼13 times longer than the electron spin lifetime (τe ∼ 0.4 ps). We ascribe the fast electron spin relaxation to the presence of strong spin–orbit coupling in the conduction band, which is ineffective for holes in the s-type valence band.

Antisemitism and polarization: the political dynamics of American Jewish concerns about traditional and Israel-related antisemitism

ABSTRACT Notwithstanding the increasing alignment between social and political identities, political divisions exist within social groups as well as between them. Despite their shared traditions, American Jews face similar political divisions as Americans in general. But could the perception of a common threat, such as antisemitism, alter the dynamics of political polarization within a social group? American Jews’ concerns about antisemitism might themselves be filtered through political identities, with liberal Jews more concerned about “traditional” antisemitism (long-standing anti-Jewish stereotypes) emanating from the political right, and conservative Jews concerned about “Israel-related” antisemitism (blaming individual Jews for the actions of Israel) associated with the political left. Using a sample of over 2000 Jewish young adults, we find that, although liberal and conservative Jews are equally concerned about traditional antisemitism, conservatives are significantly more concerned about Israel-related antisemitism than liberals. We also find that, after a series of high-profile attacks on American Jews related to the 2021 Israel–Hamas conflict, liberal and conservative Jews’ concerns about Israel-related antisemitism increased at similar rates. These results suggest that, although concerns about antisemitism are influenced by political identity, rising antisemitism is unlikely to exacerbate political polarization between liberal and conservative Jews.

Early snowmelt and polar jet dynamics co-influence recent extreme Siberian fire seasons.

The summers of 2019, 2020, and 2021 experienced unprecedented fire activity in northeastern Siberia, driven by record high spring and summer temperatures. Many of these fires burned in permafrost peatlands within the Arctic Circle. We show that early snowmelt together with an anomalous Arctic front jet over northeastern Siberia promoted unusually warm and dry surface conditions, followed by anomalously high lightning and fire activity. Since 1966, spring snowmelt has started 1.7 days earlier each decade. Moreover, Arctic front jet occurrences in summer have more than tripled in frequency over the last 40 years. These interconnected climatological drivers promote extreme fire activity in eastern Siberia, including a northward shift of fires, which may accelerate the degradation of carbon-rich permafrost peatlands.

A Model Fusion Method for Online State of Charge and State of Power Co-Estimation of Lithium-Ion Batteries in Electric Vehicles

In this paper, a model fusion method (MFM) is proposed for online state of charge (SOC) and state of power (SOP) co-estimation of lithium-ion batteries (LIBs) in electric vehicles (EVs). Firstly, a particle swarm optimization-genetic algorithm (PSO-GA) method is cooperated with a 2-RC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CPE</sub> fractional-order model (FOM) to construct battery open-circuit voltage (OCV)-SOC curve, which only relies on a part of dynamic load profile without the prior knowledge of an initial SOC. Secondly, a dual extended Kalman filter (DEKF) algorithm based on a 1-RC model is employed to identify the model parameters and estimate battery SOC with the extracted OCV-SOC curve. Furthermore, battery polarization dynamics in a SOP prediction window is analyzed from two aspects: (1) self-recovery; and (2) current excitation. They are separately simulated using 2-RC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CPE</sub> FOM and 1-RC model, and then integrated through a model fusion for online SOP estimation, which enables an analytical expression of battery peak charge/discharge current in a prediction window without weakening the nonlinear characteristic of FOM. Experimental results demonstrate the improved performance of the proposed MFM for online discharge SOP estimation, where the mean absolute error and root mean square error are only 0.288 W and 0.35 W, respectively, under the urban dynamometer driving schedule profile.

Oligomerization of peripheral membrane proteins provides tunable control of cell surface polarity

Asymmetric distributions of peripheral membrane proteins define cell polarity across all kingdoms of life. Non-linear positive feedback on membrane binding is essential to amplify and stabilize these asymmetries, but how specific molecular sources of non-linearity shape polarization dynamics remains poorly understood. Here we show that the ability to oligomerize, which is common to many peripheral membrane proteins, can play a profound role in shaping polarization dynamics in simple feedback circuits. We show that size-dependent binding avidity and mobility of membrane-bound oligomers endow polarity circuits with several key properties. Size-dependent membrane binding avidity confers a form of positive feedback on the accumulation of oligomer subunits. Although insufficient by itself, this sharply reduces the amount of additional feedback required for spontaneous emergence and stable maintenance of polarized states. Size-dependent oligomer mobility makes symmetry breaking and stable polarity more robust with respect to variation in subunit diffusivities and cell sizes, and slows the approach to a final stable spatial distribution, allowing cells to “remember” polarity boundaries imposed by transient external cues. Together, these findings reveal how oligomerization of peripheral membrane proteins can provide powerful and highly tunable sources of non-linear feedback in biochemical circuits that govern cell surface polarity. Given its prevalence and widespread involvement in cell polarity, we speculate that self-oligomerization may have provided an accessible path to evolving simple polarity circuits.

Ideological polarization during a pandemic: Tracking the alignment of attitudes toward COVID containment policies and left-right self-identification.

Research on opinion polarization has focused on growing divides in positions toward political issues between the more politically and ideologically engaged parts of the population. However, it is fundamentally difficult to track the alignment process between ideological group identity and issue positions because classically controversial political issues are already strongly associated with ideological or partisan identity. This study uses the COVID pandemic as an unique opportunity to investigate polarizing trends in the population. Pandemic management policies were not a politicized issue before COVID, but became strongly contested after governments all across the world initiated policies to contain the pandemic. We use data from the Austrian Corona Panel Project (ACPP) to track trajectories in attitudes toward current COVID measures over the course of more than a year of the pandemic. We differentiate individuals by their ideological self-identity as measured by left-right self-placement. Results suggest that all ideological groups viewed the containment measures as similarly appropriate in the very beginning. However, already in the first weeks, individuals who identify as right-wing increasingly viewed the policies as too extreme, whereas centrists and left-wing identifiers viewed them as appropriate. Opinion differences between left-wing and right-wing identifiers solidified over the course of the pandemic, while centrists fluctuated between left and right self-identifiers. However, at the end of our observation period, there are signs of convergence between all groups. We discuss these findings from the perspective of theoretical models of opinion polarization and suggest that polarization dynamics are likely to stop when the political context (salience of certain issues and concrete material threats) changes.

Phase relaxation control in heterostructures featuring charge-transfer excitons

Type-II quantum well heterostructures are considered high-potential candidates for next-generation active semiconductor devices. They promise low fundamental transition energies and suppressed Auger scattering as well as temperature stability in device performance. Understanding their fundamental properties, such as scattering and diffusion, and revealing intricate differences from type-I quantum structures are important steps towards optimized structure design. Using degenerate four-wave mixing spectroscopy, we investigate the phase coherence of excitonic polarizations in a (Ga,In)As/GaAs/Ga(As,Sb) type-II double-quantum-well structure. It is designed to exhibit spectrally isolated resonances in its linear absorption spectrum including a well-resolved charge-transfer exciton resonance. This allows us to study the coherent dynamics of the unperturbed charge-transfer exciton polarization. In addition, the effects of many-body interactions with free charge carriers as well as excitons that are injected by an optical prepulse are revealed. Scattering of charge-transfer excitons with free charge carriers is three times more efficient than scattering of charge-transfer excitons with each other. The comparison with Wannier excitons in a type-I quantum well structure shows that the interaction strength between charge-transfer excitons is about twice as large as for excitons in a type-I quantum well structure.

How digital media drive affective polarization through partisan sorting.

Politics has in recent decades entered an era of intense polarization. Explanations have implicated digital media, with the so-called echo chamber remaining a dominant causal hypothesis despite growing challenge by empirical evidence. This paper suggests that this mounting evidence provides not only reason to reject the echo chamber hypothesis but also the foundation for an alternative causal mechanism. To propose such a mechanism, the paper draws on the literatures on affective polarization, digital media, and opinion dynamics. From the affective polarization literature, we follow the move from seeing polarization as diverging issue positions to rooted in sorting: an alignment of differences which is effectively dividing the electorate into two increasingly homogeneous megaparties. To explain the rise in sorting, the paper draws on opinion dynamics and digital media research to present a model which essentially turns the echo chamber on its head: it is not isolation from opposing views that drives polarization but precisely the fact that digital media bring us to interact outside our local bubble. When individuals interact locally, the outcome is a stable plural patchwork of cross-cutting conflicts. By encouraging nonlocal interaction, digital media drive an alignment of conflicts along partisan lines, thus effacing the counterbalancing effects of local heterogeneity. The result is polarization, even if individual interaction leads to convergence. The model thus suggests that digital media polarize through partisan sorting, creating a maelstrom in which more and more identities, beliefs, and cultural preferences become drawn into an all-encompassing societal division.

Probing Temperature‐Induced Phase Transitions at Individual Ferroelectric Domain Walls

AbstractFerroelectric domain walls have emerged as one of the most fascinating objects in condensed matter physics due to the broad variability of functional behaviors they exhibit. However, the vast majority of domain walls studies have been focused on bias‐induced dynamics and transport behaviors. Here, the scanning probe microscopy approach based on piezoresponse force microscopy (PFM) with a dynamically heated probe, combining local heating and local biasing of the material is introduced. This approach is used to explore the thermal polarization dynamics in soft Sn2P2S6 ferroelectrics, and allows for the exploration of phase transitions at individual domain walls. The strong and weak modulation regimes for the thermal PFM are introduced. The future potential applications of heated probe approach for functional SPM measurements including piezoelectric, elastic, microwave, and transport measurements are discussed.

Effect of Twisting Phases on the Polarization Dynamics of a Vector Optical Field

The effect of twisting phases on the polarization dynamics of a vector vortex beam with a spatially variant state of polarization (SoP) is investigated theoretically and experimentally. The twisted vector vortex optical field with the cross-phase modulation is experimentally generated and observed. The presence of the twisting phases on the vector optical field results in novel propagation dynamics and the evolution of polarization states. The optical field performs the process of compressing and stretching the orthogonal polarization components and the linear-circular polarization conversions during propagation. Different from the scalar twisted beams, the orthogonal polarization components of twisted vector beams can be compressed along the same azimuthal angle or the orthogonal azimuthal angles, depending on the signs of the twist intensity coefficients. For an anisotropic twisted optical field, the SoP and the optical field rotate, and the rotation behaviors are sensitively dependent on the twisting coefficients. Furthermore, the two vortex topological charges embedded within the orthogonal polarization component of a twisted vector vortex beam can be simultaneously identified by looking at the interference fringes of the twisting phases. This work reveals that a vector vortex beam and its SoP can be dynamically manipulated by twisting phases.

Characteristic Study on Parallel Reservoir Computation Based on VCSEL Dynamics With Optoelectronic Feedback

We proposed a new reservoir computation (RC) structure using polarization dynamics of vertical cavity surface emitting lasers (VCSELs) with optoelectronic feedback. Santa-Fe time-series prediction and nonlinear channel equalization were used to evaluate its parallel processing capability. We numerically discussed the effects of feedback strength, injection strength, frequency detuning, injection current and scaling factors on the RC performance of the system. The results show that, the operation range of negative feedback is larger than that of positive feedback; under appropriate feedback and lager injection strengths, good RC performance can be achieved for a wider injection current; with continuous variation of feedback strength from negative to positive values, the optimized location for frequency detuning moves from positive to negative values. We also evaluated the processing rate of proposed RC structure. The related study is helpful for the design and optimization of VCSEL-based RC under optoelectronic feedback.

Geometry Adaptation of Protrusion and Polarity Dynamics in Confined Cell Migration

Cell migration in confining physiological environments relies on the concerted dynamics of several cellular components, including protrusions, adhesions with the environment, and the cell nucleus. However, it remains poorly understood how the dynamic interplay of these components and the cell polarity determine the emergent migration behavior at the cellular scale. Here, we employ a data-driven theoretical approach to develop a mechanistic model for confined cell migration, revealing how the cellular dynamics adapt to confining geometries. Specifically, we use experimental data of joint protrusion-nucleus migration trajectories of cells on confining micropatterns to systematically determine a model linking the stochastic dynamics of cell polarity, protrusions, and nucleus. Our model indicates that the cellular dynamics adapt to confining constrictions through a switch in the polarity dynamics from a negative to a positive, self-reinforcing feedback loop. This feedback loop leads to stereotypical cycles of protrusion-nucleus dynamics that drive the migration of the cell through constrictions. Our data-driven theoretical approach therefore identifies polarity feedback adaptation as a key mechanism in confined cell migration.