Global Polarization Research Articles

Topological polarization singularities in metaphotonics

AbstractPolarization singularities of vectorial electromagnetic fields locate at the positions where properties of polarization ellipses are not defined. First observed for conical diffraction in 1830s, polarization singularities have been studied systematically with the underlying concepts being reshaped and deepened by many pioneers of wave optics. Here we review the recent results on the generation and observation ofpolarization singularities in metaphotonics. We start with the discussion of polarization singularities in the Mie theory, where both electric and magnetic multipoles are explored from perspectives of local and global polarization properties. We then proceed with the discussion of various photonic-crystal structures, for which both near- and far-field patterns manifest diverse polarization singularities characterized by the integer Poincaré or more general half-integer Hopf indices (topological charges). Next, we review the most recent studies of conversions from polarization to phase singularities in scalar wave optics, demonstrating how bound states in the continuum can be exploited to generate directly optical vortices of various charges. Throughout our paper, we discuss and highlight several fundamental concepts and demonstrate their close connections and special links to metaphotonics. We believe polarization singularities can provide novel perspectives for light-matter manipulation for both fundamental studies and their practical applications.

Hydrodynamic study of hyperon spin polarization in relativistic heavy ion collisions

We perform a systematic study of the spin polarization of hyperons in heavy-ion collisions using the MUSIC hydrodynamic model with A Multi-Phase Transport (AMPT) pre-equilibrium dynamics. Our model calculations nicely describe the measured collision-energy, centrality, rapidity, and $p_T$ dependence of $\Lambda$ polarization. We also study and predict the global spin polarization of $\Xi^-$ and $\Omega^-$ as a function of collision energy, which provides a baseline for the studies of the magnetic moment, spin, and mass dependence of the spin polarization. For the local spin polarization, we calculate the radial and azimuthal components of the transverse $\Lambda$ polarization and find specific modulating behavior which could reflect the circular vortical structure. However, our model fails to describe the azimuthal-angle dependence of the longitudinal and transverse $\Lambda$ polarization, which indicates that the hydrodynamic framework with the spin Cooper-Frye formula under the assumption of thermal equilibrium of spin degree of freedom needs to be improved.

Spectropolarimetry of Primitive Phototrophs as Global Surface Biosignatures.

Photosynthesis is an ancient metabolic process that began on early Earth and offers plentiful energy to organisms that can utilize it such that that they achieve global significance. The potential exists for similar processes to operate on habitable exoplanets and result in observable biosignatures. Before the advent of oxygenic photosynthesis, the most primitive phototrophs, anoxygenic phototrophs, dominated surface environments on the planet. Here, we characterize surface polarization biosignatures associated with a diverse sample of anoxygenic phototrophs and cyanobacteria, examining both pure cultures and microbial communities from the natural environment. Polarimetry is a tool that can be used to measure the chiral signature of biomolecules. Chirality is considered a universal, agnostic biosignature that is independent of a planet's biochemistry, receiving considerable interest as a target biosignature for life-detection missions. In contrast to preliminary indications from earlier work, we show that there is a diversity of distinctive circular polarization signatures, including the magnitude of the polarization, associated with the variety of chiral photosynthetic pigments and pigment complexes of anoxygenic and oxygenic phototrophs. We also show that the apparent death and release of pigments from one of the phototrophs is accompanied by an elevation of the reflectance polarization signal by an order of magnitude, which may be significant for remotely detectable environmental signatures. This work and others suggest that circular polarization signals up to ∼1% may occur, significantly stronger than previously anticipated circular polarization levels. We conclude that global surface polarization biosignatures may arise from anoxygenic and oxygenic phototrophs, which have dominated nearly 80% of the history of our rocky, inhabited planet.

Underwater degraded image–sharpening method based on optimal polarization parameter reconstruction

In order to solve the problems of blurred image and low contrast caused by the absorption and scattering of underwater light by turbid water, an algorithm of underwater image optimal restoration based on global polarization parameter estimation was proposed. Firstly, the local minimum filter was used to estimate the underwater background light image, Stokes vector principle was introduced to calculate the degree of polarization image, and normalized mutual information was used to further optimize the degree of polarization information, to obtain the best reconstructed polarization parameters in the imaging region. Secondly, a method of image reconstruction based on morphology was used to estimate the infinite underwater background light intensity values automatically. Finally, the underwater simulated environment platform was built, and the underwater polarization image was acquired in real time through a single channel fast rotating polarization detector. In order to verify the effectiveness of the algorithm, the three objective evaluation indexes were adopted as quantification to evaluate indexes factors. The results show that the algorithm is better than the other underwater image restoration methods.

Differential measurements of Λ polarization in Au+Au collisions and a search for the magnetic field by STAR

Global hadron polarization, P¯H, was measured by the STAR collaboration through the Λ hyperon, confirming the existence of extremely large vorticities within the Quark-Gluon Plasma (QGP). A recent study using high-statistics data set at sNN=200GeV has shown that P¯H depends on collision centrality, azimuthal angle, ϕ, transverse momentum, pT, and pseudorapidity, η. We extend these differential measurements to the collision energies of sNN=54.4and27GeV, using three different detectors for the event-plane determination. Additionally, there is a suggested enhancement P¯Λ¯ relative to P¯Λ across all beam energies; however, the statistics are too limited to make a significant measurement. A recent, high-statistics data set of Au+Au collisions at sNN=27GeV includes improved event-plane resolution; we discuss the feasibility of using this data set to study the possible splitting between P¯Λ and P¯Λ¯.

STAR Highlights

In this overview talk, I have represented STAR to highlight the results of 19 parallels talks and 38 posters at this Quark Matter Conference. The contents have 8 major categories: 1. experimental measurements related to the Breit-Wheeler process and vacuum birefringence; 2. probes of initial states of heavy-ion collisions (parton distribution function and azimuthal correlations in small systems); 3. constraints on temperature-dependent viscosity (η/s(T)) with multiple flow harmonics and rapidity correlations; 4. hard probes using jet structures and heavy flavors; 5. exploration of the origin of global polarization and vorticity; 6. chiral and thermal properties of the QGP; 7. Beam Energy Scan (BES) and the critical point search; 8. upgrades and summary.

Magnetic Field in the Charged Subatomic Swirl

We report a novel relation between rotation and magnetic field in a charged fluid system: there is naturally a magnetic field along the direction of fluid vorticity due to the currents associated with the swirling charges. This general connection is demonstrated using a fluid vortex. Applying the idea to heavy ion collisions we propose a new mechanism for generating in-medium magnetic field with a relatively long lifetime. We estimate the magnitude of this new magnetic field in the Au-Au colliding systems across a wide span of collisional beam energy. Such a magnetic field is found to increase rapidly toward lower beam energy and could account for a significant amount of the experimentally observed global polarization difference between hyperons and anti-hyperons.

Global hyperon polarization in Au+Au collisions at in the STAR experiment

The Quark-Gluon Plasma (QGP), appearing in non-central nucleus-nucleus collisions is generated with large orbital angular momentum. Spin-orbit coupling aligns spin directions of produced particles with the system angular momentum, through the creation of local vorticity. Properties of hyperon weak decays lead to the way of measuring polarization, that reflects vorticity. The global polarization of Λ and hyperons was measured for Au+Au collisions at recorded with the STAR at the RHIC. However, different theoretical approaches are still in need of new experimental input to describe global polarization properly. That’s why it is important to measure the global polarization of different particle species. In this paper, we will report new results of hyperon global polarization ( and ) measurement via different methods for high-statistics Au+Au collisions at .

A magic formula for economic development? Global market integration and spatial polarization in extractive industries

ABSTRACT The World Bank, World Trade Organization and others promote integration into global markets as a certain path towards economic development. Some researchers share this optimism, arguing that development is the record of how one thing leads to another, once peripheral locations have plugged into global networks. Comparing resource peripheries in South America, Southeast Asia and Sub-Saharan Africa with regard to the upstream oil and gas sector, we call for a more nuanced assessment. Against the backdrop of 38 narrative, open-ended interviews, we show that there is spatial polarization between ‘gateways’ and peripheral sites in Southeast Asia. Argentinean and Ghanaian case studies reveal that local firms usually provide generic services, with little prospects of venturing into higher value-adding activities. We conclude that at least the oil and gas sector is not suitable for fulfilling very optimistic expectations on development.

Predicting the Future: Art and Algorithms

AbstractPredictive algorithms are replacing the art of human judgement in rapidly growing areas of social life. By offering pattern recognition as forecast, predictive algorithms mechanically project the past onto the future, embracing a peculiar notion of time where the future is different in no radical way from the past and present, and a peculiar world where human agency is absent. Yet, prediction is about agency, we predict the future to change it. At the individual level, the psychological literature has concluded that in the realm of predictions, human judgement is inferior to algorithmic methods. At the sociological level, however, human judgement is often preferred over algorthms. We show how human and algorithmic predictions work in three social contexts—consumer credit, college admissions and criminal justice—and why people have good reasons to rely on human judgement. We argue that mechanical and overly successful local predictions can result in self-fulfilling prophecies and, eventually, global polarization and chaos. Finally, we look at algorithmic prediction as a form of societal and political governance and discuss how it is currently being constructed as a wide net of control by market processes in the USA and by government fiat in China.

Rapidity dependence of global polarization in heavy ion collisions * *ZTL and QW are supported in part by the National Natural Science Foundation of China (NSFC) (11890713, 11535012). JS is supported in part by Shandong Province Natural Science Foundation (ZR2019YQ06)

We use a geometric model for hadron polarization in heavy ion collisions with an emphasis on the rapidity dependence. The model is based on the model of Brodsky, Gunion, and Kuhn, as well as the Bjorken scaling model. We make predictions regarding the rapidity dependence of global polarization in the collision energy range of 7.7-200 GeV by assuming the rapidity dependence of two parameters, and . The predictions can be tested by future beam-energy-scan experiments at the Relativistic Heavy Ion Collider of Brookhaven National Lab.

Global polarization in heavy-ion collisions based on the axial vortical effect

Global polarization of $\Lambda$ and $\bar{\Lambda}$ is calculated based on the axial vortical effect (AVE). Simulations are performed within the model of the three-fluid dynamics. Equations of state with the deconfinement transition result in a good agreement with STAR data for both $\Lambda$ and $\bar{\Lambda}$ polarization, in particular, with the $\Lambda$-$\bar{\Lambda}$ splitting. Suppression of the gravitational-anomaly contribution required for the data reproduction is in agreement with predictions of the QCD lattice simulations. Predictions for the global polarization in forthcoming experiments at lower collision energies are made. These forthcoming data will provide a critical test for the AVE and thermodynamic mechanisms of the polarization.

Indonesia's Defense Diplomacy through the United States: Case Study of Cooperation a Float Readiness and Training (CARAT) 2019 Joint Exercise

Global dan regional constellation shows a rapid dynamic after the cold war ended. Global polarity turned to multipolar at the same time the center of gravity of international relations has shifted to Asia-Pacific. Indonesia geographically and strategically in the central position regarded to the reality above. US rebalancing policy brings Indonesia to a geopolitical rivalry among great powers. Indonesia committed to Free and Active policy which means do not side to any political blocs but keep active to prevent conflict in the international system by cooperation approach. This research aimed to discuss Indonesia's defense diplomacy to US through joint exercise of Cooperation Afloat Readiness and Training (CARAT) by 2019. The research is qualitative research with a case study approach. Depth exploration conducted by the researcher over the case of CARAT exercise supported by the main analysis tool of defense diplomacy theory which explaining that joint exercise is one of the activities aimed to reach a confidence-building measure (CBMs) and defense capability building. To describe Indonesia's foreign policy towards US within the contemporary political environment, this writing uses the theory of foreign policy and theory of strategy. As an initial conclusion, the joint military exercise of CARAT 2019 successfully strengthening mutual trust and mutual understanding between Indonesia and US in addition to improving Indonesia's military skill which is crucial in the current global political situation.

Core meets corona: A two-component source to explain Λ and [formula omitted] global polarization in semi-central heavy-ion collisions

We compute the Λ and Λ‾ global polarization in semi-central heavy-ion collisions modeling the source as consisting of a high-density core and a less dense corona. We show that when more Λs than Λ‾s are produced in the corona, and this is combined with a smaller number of Λs coming from the core, as compared to those coming from the corona, an amplification effect for the Λ‾ with respect to that of Λ polarization can occur. This amplification becomes more important for lower collision energies and quantitatively accounts for the Λ and Λ‾ polarizations measured by the STAR beam energy scan.

Regional Magnetostratigraphy of the Upper Cretaceous and the Cretaceous–Paleogene Boundary in Southern West Siberia as Applied to Complitation of the Cretaceous Magnetic-Polarity Scale

Abstract —Magnetostratigraphic data from wells in southern West Siberia that strip the Upper Cretaceous and Cretaceous–Paleogene boundary strata in three areas (three wells in the Omsk Basin, two wells in the Bakchar Iron Basin, and two wells in the southern Kulunda Basin) are used to compile the respective regional magnetic-polarity scale. According to the available biostratigraphic constraints, the deposition spanned the period from Albian to Bartonian. The reported regional polarity scale is based on integrated paleomagnetic and biostratigraphic data from the seven wells and comprises four Upper Cretaceous zones of normal (NK1-2(al-st) and NK2mt) and reverse (RK2km and RK2mt) polarity corresponding to the C34, C33r, C31r, and C30n Chrons of the global magnetic polarity scale and four Paleogene zones of reverse polarity: R1E1zl, R2E1t, R1E2t-i(?), and R1E2l-b, with the first two correlating with the C26r and C25r Chrons. Some of the Upper Cretaceous magnetozones enclose thin intervals (microzones) of the opposite polarity. The regional Cretaceous–Paleogene magnetic-polarity scale of southern West Siberia reveals several deposition gaps from 6 to 28 Myr long. The magnetostratigraphic data can be used to determine deposition rates and can make reference for local, regional, and global correlations of geologic events given that polarity reversals are of global extent.

Correlation between global polarization, angular momentum, and flow in heavy-ion collisions

Possible correlations of the global polarization of $\Lambda$ hyperons with the angular momentum and transverse flow in the central region of colliding nuclei are studied based on refined estimate of the global polarization. Simulations of Au+Au collisions at collision energies $\sqrt{s_{NN}}=$ 6-40 GeV are performed within the model of the three-fluid dynamics. Within the crossover and first-order-phase-transition scenarios this refined estimate quite satisfactorily reproduces the experimental STAR data. Hadronic scenario fails at high collision energies, $\sqrt{s_{NN}}>$ 10 GeV, and even predicts opposite sign of the global polarization. It is found that the global polarization correlates with neither the angular momentum accumulated in the central region nor with directed and elliptic flow. At the same time we observed correlation between the angular momentum and directed flow in both their time and collision-energy dependence. These results suggest that, although initially the angular momentum is the driving force for the vortex generation, later the angular momentum and vortex motion become decorrelated in the midrapidity region. Then the midrapidity angular momentum is determined by the pattern of the directed flow and even becomes negative when the antiflow occurs. At the freeze-out stage, the dominant part of the participant angular momentum is accumulated in the fragmentation regions.

Spectral induced polarization study on enzyme induced carbonate precipitations: influences of size and content on stiffness of a fine sand

Heterogeneity in either chemically or microbiologically induced carbonate-based ground improvement methods is a major obstacle in engineering application. Spectral induced polarization (SIP), an innovative and nondestructive method, which has demonstrated promise in monitoring microbial activity, was used in this study to monitor enzyme induced carbonate precipitation (EICP). The complex conductivities, together with the shear wave velocities (Vs), of an EICP modified sand were monitored using a self-developed spectral induced polarization–bender element column. The mean precipitate size was calculated by relaxation time (τ) and the Schwarz equation. The precipitate contents were calculated by cumulative gamma distribution function on the global polarization magnitude (mn) with R2 = 0.989. The stiffness of the enhanced geomaterial, in terms of Vs, correlates to mn with a cumulative lognormal distribution function with R2 = 0.967. Contact cementation was postulated as the dominant association pattern. The possible mechanism for this may be the formation of eddies and the nucleation of CaCO3 crystals during precipitation. The results suggest that SIP can be used as an effective nondestructive monitoring tool to assess the stiffness of geomaterials.

The value of asymmetry: how polarity proteins determine plant growth and morphology.

Cell polarity is indispensable for forming complex multicellular organisms. Proteins that polarize at specific plasma membrane domains can either serve as scaffolds for effectors or coordinate intercellular communication and transport. Here, I give an overview of polarity protein complexes and their fundamental importance for plant development, and summarize novel mechanistic insights into their molecular networks. Examples are presented for proteins that polarize at specific plasma membrane domains to orient cell division planes, alter cell fate progression, control transport, direct cell growth, read global polarity axes, or integrate external stimuli into plant growth. The recent advances in characterizing protein polarity during plant development enable a better understanding of coordinated plant growth and open up intriguing paths that could provide a means to modulate plant morphology and adaptability in the future.

Elevated paleomagnetic dispersion at Saint Helena suggests long-lived anomalous behavior in the South Atlantic

Earth's magnetic field is presently characterized by a large and growing anomaly in the South Atlantic Ocean. The question of whether this region of Earth's surface is preferentially subject to enhanced geomagnetic variability on geological timescales has major implications for core dynamics, core-mantle interaction, and the possibility of an imminent magnetic polarity reversal. Here we present paleomagnetic data from Saint Helena, a volcanic island ideally suited for testing the hypothesis that geomagnetic field behavior is anomalous in the South Atlantic on timescales of millions of years. Our results, supported by positive baked contact and reversal tests, produce a mean direction approximating that expected from a geocentric axial dipole for the interval 8 to 11 million years ago, but with very large associated directional dispersion. These findings indicate that, on geological timescales, geomagnetic secular variation is persistently enhanced in the vicinity of Saint Helena. This, in turn, supports the South Atlantic as a locus of unusual geomagnetic behavior arising from core-mantle interaction, while also appearing to reduce the likelihood that the present-day regional anomaly is a precursor to a global polarity reversal.

De enscenering van verzet tegen een wereldmaatschappij

Abstract The mise en scène of resistance against a global society. An analysis of (a)symmetrical distinctions The concept of oikophobia is often used as an answer and rebuttal to the accusation of xenophobia that is often raised against nationalist groups. Oikophobia denounces the image of nationalists as people who first and foremost hate what is foreign or the foreigner. They describe themselves, on the contrary, as having a strong attachment to their own culture and their opponents as having a fear of or aversion to their origin or (cultural) home. This game of asymmetrical descriptions is the subject of this contribution, which focuses on the logic of distinctions that lies behind this resistance to (hostile) images. What then also lights up is that the global polarization we see between nationalist and cosmopolitan movements also concerns the status of asymmetrical distinctions themselves. The nationalist resistance to world society can be interpreted as a resistance to the becoming symmetrical of existential distinctions, i.e. distinctions that create identity and belonging.