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1
Wirth, M., E. Bogner, and F. Gabor. "Parameters influencing the transport rate of marker compounds across Caco-2 monolayers." Scientia Pharmaceutica 69, no. 1 (March 30, 2001): 91–104. http://dx.doi.org/10.3797/scipharm.aut-01-11.
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Performing transport experiments with Caco-2 monolayers some important parameters have to be considered. Cell layers are appropriate for transport studies after complete polarisation and differentiation. Consequently they should be used 20 - 25d after seeding. Monolayers grown for shorter time than 20d yield to high transport rates, a cultivation period longer than 25d results in layers susceptible to detachment. Additionally the material of the filter support exerts an influence on the transport data because of varying barrier functions of cell layers grown on polyester- versus polycarbonate filter inserts. By comparison of transport rates obtained with different model systems such as Transwells and Ussing chambers the influence of the unstirred water layer on permeation of markers was investigated. The results indicate that there is a noticeable difference with hydrophobic compounds only. To check the dependence of transport phenomena on energy the difference in transport rates between 4°C and 37°C as well as the cumulative transport subject to the transport direction was determined. Moreover the influence of the stirring rate on the cumulative transport in the Ussing chamber system was elucidated. For assessment of the cell associated amount of the transported substance the cell layer was dissolved in NaOH / SDS to get further valuable informations.
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Piltyay, Stepan, Andrew Bulashenko, Hanna Kushnir, and Oleksandr Bulashenko. "Information Resources Economy in Satellite Systems based on New Microwave Polarizers with Tunable Posts." Path of Science 6, no. 11 (November 30, 2020): 5001–10. http://dx.doi.org/10.22178/pos.64-6.
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One of the fundamental problems of modern digital telecommunications is the economy of digital information and frequency resources, which are highly limited. The introduction of novel telecommunication systems and 5G networks requires searching for principal solutions for the economy and reusing the frequency spectrum. Therefore, modern wireless mobile, terrestrial, and satellite systems use various new technologies to increase communication channels' information capacity for the economy of limited frequency resources. One of the most effective ways to reuse the information system's operating frequency band is to apply antennas with polarisation signal processing. Such systems provide the possibility to transmit and to receive simultaneously signals with different types of polarisation. Consequently, the application of electromagnetic waves with two orthogonal polarisations improves wireless systems' information characteristics for various purposes. This allows doubling the information capacity of mobile, terrestrial, and satellite communication channels. Also, polarisation processing is carried out in meteorological and radar systems to receive, transmit, and process information. The essential elements of such systems are microwave polarisers and orthomode transducers. The electromagnetic characteristics of these devices affect the aspects of the whole system significantly. Main electromagnetic factors include phase, matching, and polarisation parameters. The article presents the development of a compact tunable polarizer based on a square waveguide with three posts. The developed polariser operates in the X-band from 8.0 GHz to 8.5 GHz. Created a mathematical model of the polariser is based on the scattering and transmission matrices. To verify the developed theoretical model's correctness, the calculation of all characteristics was also performed numerically using the finite integration technique. The developed compact polariser based on a square waveguide with three posts allows tuning it's matching and polarisation characteristics by changing all posts' heights. The developed polariser's main advantages are small dimensions, tuning options, and aspects of polarisation transformation.
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Eriksson, P., B. Rydberg, and S. A. Buehler. "On cloud ice induced absorption and polarisation effects in microwave limb sounding." Atmospheric Measurement Techniques 4, no. 6 (June 30, 2011): 1305–18. http://dx.doi.org/10.5194/amt-4-1305-2011.
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Abstract. Microwave limb sounding in the presence of ice clouds was studied by detailed simulations, where clouds and other atmospheric variables varied in three dimensions and the full polarisation state was considered. Scattering particles were assumed to be horizontally aligned oblate spheroids with a size distribution parameterized in terms of temperature and ice water content. A general finding was that particle absorption is significant for limb sounding, which is in contrast to the down-looking case, where it is usually insignificant. Another general finding was that single scattering can be assumed for cloud optical paths below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrieval algorithms. The representation of particle sizes during the retrieval is also discussed. Concerning polarisation, specific findings were as follows: Firstly, no significant degree of circular polarisation was found for the considered particle type. Secondly, for the ±45° polarisation components, differences of up to 4 K in brightness temperature were found, but differences were much smaller when single scattering conditions applied. Thirdly, the vertically polarised component has the smallest cloud extinction. An important goal of the study was to derive recommendations for future limb sounding instruments, particularly concerning their polarisation setup. If ice water content is among the retrieval targets (and not just trace gas mixing ratios), then the simulations show that it should be best to observe any of the ±45° and circularly polarised components. These pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations.
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Moine, Monique, Henri Giraud, and Anne Puissant. "Mise en place d'une méthode semi-automatique de cartographie de l'occupation des sols à partir d'images SAR polarimétriques." Revue Française de Photogrammétrie et de Télédétection, no. 215 (August 16, 2017): 13–23. http://dx.doi.org/10.52638/rfpt.2017.319.
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Les cartes d'occupation du sol produites à des résolutions spatiales et temporelles élevées constituent actuellement une ressource très importante pour beaucoup d'organismes privés ou publics. Le développement de méthodes de cartographie automatique, fiables et robustes basées sur la classification d'images satellites constitue ainsi un enjeu majeur. Dans ce cadre, l'imagerie radar apporte l'avantage de fournir des images de jour comme de nuit, et quelles que soient les conditions météorologiques. Plus récemment, l'exploitation des informations de rétrodiffusion fournies par les images SAR (Synthetic Aperture Radar) polarimétriques a permis d'étendre les possibilités apportées par l'imagerie radar. Dans cette étude, une carte d'occupation du sol a été produite sur une partie de la plaine d'Alsace et du massif vosgien à partir (1) de 76 paramètres polarimétriques extraits d'une image ALOS PALSAR en polarisation quadruple et (2) d'une méthode de classification orientée-objet. Plusieurs algorithmes de classification ont été testés et l'algorithme du plus proche voisin est ressorti comme donnant les meilleurs résultats. La méthode mise en place à l'avantage d'être semi-automatique et facilement reproductible. Neuf classes d'occupation du sol ont été cartographiées avec un taux de bon classement de 69%. Plus précisément, trois d'entre elles ont été très correctement détectées : la forêt, l'urbain et l'eau. D'autres classes ont été confondues du fait de la similarité de leur signature polarimétrique : les zones de vignobles, les prairies et les zones de cultures. Enfin, trois classes non visibles sur les données a priori et les images optiques de référence ont pu être identifiées sur l'image polarisée. Ces premiers résultats sont prometteurs pour la cartographie de l'occupation des sols à partir d'images SAR polarimétriques.
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Hoang, Kim Huong, Monique Bernier, Sophie Duchesne, and Minh Y Tran. "Renforcement de la qualité d’information de l’occupation du sol par l’intégration de données satellitaires optiques et radar en support à la modélisation hydrologique." Revue des sciences de l’eau 31, no. 3 (December 10, 2018): 177–99. http://dx.doi.org/10.7202/1054302ar.
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Afin de suivre l’évolution de l’occupation du sol du bassin versant de la rivière Cau (nord du Vietnam), des images HRVIR 2 du satellite SPOT-4 ont été acquises fin novembre 2007 et début janvier 2008. Dans un premier temps, l’approche de classification hiérarchique avec le mode de classification « avec caractéristiques liées aux classes (class-related features) » a été développée et appliquée afin d’extraire sept classes d’occupation du sol pertinentes à la modélisation hydrologique, sans distinguer les rizières des autres types de culture. Cette approche a montré son efficacité, la précision globale de la classification étant de 91 %. Une diminution significative de la confusion entre les milieux urbains, les terres agricoles et les plantations a été remarquée par rapport à une classification antérieure d’une image LANDSAT-7 de 2003, dont la précision globale était de 78 %. Par la suite, afin de distinguer les rizières des autres types de culture, deux séries d’images du satellite RADARSAT-2 en bande-C (double polarisation et polarimétriques) ont été utilisées. Ces images ont été acquises de mai 2009 à mai 2010 et couvrent deux périodes de croissance du riz, soit la période de la principale récolte (saison traditionnelle du riz) et celle du printemps. Pour les images double polarisation, en mode standard (S5), une méthode de seuillage a été appliquée sur la variation temporelle du signal entre les images acquises en début de saison et celles à la mi-saison. Cette méthode a permis de détecter 74 % des rizières de la saison traditionnelle du riz et 63 % des rizières de la saison de riz du printemps, selon une comparaison avec des données statistiques de la province de Thai Nguyen. La précision globale de la classification obtenue, pour toutes les classes d’occupation du sol, est de 71 % pour la saison traditionnelle de riz et de 67 % pour la saison de riz du printemps. Pour les images polarimétriques, en mode fin (FQ21), la matrice de cohérence a été choisie pour identifier les rizières d’une zone hétérogène. La classification a été réalisée à l’aide de l’algorithme SVM (Support Vector Machine). Ces dernières informations ont ensuite été intégrées à la carte thématique dérivée d’images SPOT-4 pour obtenir la carte finale. Cette carte sert directement à la modélisation hydrologique. Les calculs des besoins en eau pour la culture du riz ont montré que les rizières prennent une grande proportion du débit total dans les deux sous-bassins versants utilisés en exemple. Ces calculs montrent l’importance de détecter les rizières si l’on souhaite réaliser des simulations hydrologiques réalistes sur le bassin versant de la rivière Cau et confirment une des hypothèses de nos travaux, qui est que l’identification des rizières sur la carte d’occupation du sol améliore les évaluations et prédictions liées au cycle hydrologique.
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Bugg, D. V. "Experiments Needed in Meson and Baryon Spectroscopy." Advances in High Energy Physics 2007 (2007): 1–14. http://dx.doi.org/10.1155/2007/52750.
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Three (or four) straightforward experiments would contribute greatly to completing the spectroscopy of baryons and light mesons. In the baryon sector, data are needed on inelastic reactions from a polarised target withπ±andK±beams up to∼3 GeV/c. Similar data are needed in the light meson sector forp¯pinteractions in the momentum range 0.3–2 GeV/c. In both cases, valuable information is to be obtained from longitudinal (L) and sideways (S) target polarisations as well as the conventional normal (N) polarisation. Thirdly,3S1and3D1mesons in the mass range 1–2.4 GeV could probably be separated either by diffractive dissociation of transversely polarised photons or bye+e−radiative return experiments using transversely and longitudinally polarised electrons.
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Eriksson, P., and B. Rydberg. "On cloud ice induced absorption and polarisation effects in microwave limb sounding." Atmospheric Measurement Techniques Discussions 4, no. 2 (March 2, 2011): 1493–531. http://dx.doi.org/10.5194/amtd-4-1493-2011.
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Abstract. Detailed simulations of microwave limb sounding in the presence of ice clouds have been performed. It is clarified that, while particle absorption normally gives no significant change of the measured radiance for down-looking measurements, this is not the case for limb sounding. The particles were treated as horizontally aligned oblate spheroids and for this assumption on particle shape, and comparable situations, no significant degree of circular polarisation is generated. Differences between the brightness temperature of the ±45° polarisation components up to 4 K were found, but this difference appears to be small as long as single scattering conditions apply. The cloud extinction is the smallest for the vertically polarised component, but it should be more beneficial to observe any of the ±45° and circularly polarised components if ice water content is also a target of the retrievals. These latter pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations. The results indicate that single scattering can be assumed for cloud optical thicknesses below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrievals. The representation of particle sizes during the retrieval is discussed.
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Carrillo, Juan D., and Micael Castanheira. "Information and Strategic Political Polarisation." Economic Journal 118, no. 530 (June 28, 2008): 845–74. http://dx.doi.org/10.1111/j.1468-0297.2008.02152.x.
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Savage, Sara, Emily Oliver, Ellen Gordon, and Lucy Tutton. "Addressing social polarization through critical thinking: Theoretical application in the “Living Well With Difference” course in secondary schools in England." Journal of Social and Political Psychology 9, no. 2 (September 21, 2021): 490–505. http://dx.doi.org/10.5964/jspp.7037.
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Responding to international calls for critical thinking programs to address social polarisations and extremism through education, this article examines the cognitive and socio-psychological foundations of a critical thinking programme for secondary schools in England called “Living Well With Difference” (LWWD). The aim of LWWD is to develop critical thinking about issues of social polarisation, prejudice and any kind of extreme thinking. These issues often involve the interaction of emotion and thinking, which is understood using a dual systems framework, illustrated with examples of course methodology and content. The learning process aims to promote more cognitively flexible, complex and integrated thinking, measured by integrative complexity, and is supported by meta-awareness to enable emotion management. The aim is for participants to engage with difficult social issues through structured group activities, while becoming aware of social, emotional, textual, visual and rhetorical influences to increase Media Information Literacy, as a foundation for engaging with differing perspectives in order to reduce barriers between groups in society.
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Breathnach, Proinnsias. "Social Polarisation in the Post-Fordist Informational Economy: Ireland in International Context." Irish Journal of Sociology 11, no. 1 (May 2002): 3–22. http://dx.doi.org/10.1177/079160350201100101.
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This paper examines the processes whereby post-Fordist economic restructuring is widely held to have led to growing social polarisation in the advanced capitalist economies. Conceptual fuzziness has clouded the polarisation hypothesis, and a review of international evidence shows no clear trend towards either occupational or earnings inequality. There is stronger evidence of growing household income inequality, due mainly to changes in household composition and national taxation and social welfare policies. In the case of the Republic of Ireland, there has been a more definite tendency towards occupational, earnings and household income polarisation in the 1990s, giving rise to important policy implications at a time of unprecedented national prosperity.
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Macquart, Jean-Pierre. "Circular Polarisation in AGN." Publications of the Astronomical Society of Australia 19, no. 1 (2002): 43–48. http://dx.doi.org/10.1071/as01086.
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AbstractWe discuss the constraints that recent observations place on circular polarisation in AGN. In many sources the circular polarisation is variable on short timescales, indicating that it originates in compact regions of the sources. The best prospects for gleaning further information about circular polarisation are high resolution VLBI and scintillation ‘imaging’ which probe source structure on milliarcsecond and microarcsecond scales respectively.
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Adams, Johnathan A., Gentry White, and Robyn P. Araujo. "Mathematical measures of societal polarisation." PLOS ONE 17, no. 10 (October 4, 2022): e0275283. http://dx.doi.org/10.1371/journal.pone.0275283.
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In opinion dynamics, as in general usage, polarisation is subjective. To understand polarisation, we need to develop more precise methods to measure the agreement in society. This paper presents four mathematical measures of polarisation derived from graph and network representations of societies and information-theoretic divergences or distance metrics. Two of the methods, min-max flow and spectral radius, rely on graph theory and define polarisation in terms of the structural characteristics of networks. The other two methods represent opinions as probability density functions and use the Kullback–Leibler divergence and the Hellinger distance as polarisation measures. We present a series of opinion dynamics simulations from two common models to test the effectiveness of the methods. Results show that the four measures provide insight into the different aspects of polarisation and allow real-time monitoring of social networks for indicators of polarisation. The three measures, the spectral radius, Kullback–Leibler divergence and Hellinger distance, smoothly delineated between different amounts of polarisation, i.e. how many cluster there were in the simulation, while also measuring with more granularity how close simulations were to consensus. Min-max flow failed to accomplish such nuance.
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Francfort, Jérémie, Giulia Cusin, and Ruth Durrer. "Image rotation from lensing." Classical and Quantum Gravity 38, no. 24 (November 23, 2021): 245008. http://dx.doi.org/10.1088/1361-6382/ac33ba.
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Abstract Forthcoming radio surveys will include full polarisation information, which can be potentially useful for weak lensing observations. We propose a new method to measure the (integrated) gravitational field between a source and the observer, by looking at the angle between the morphology of a radio galaxy and the orientation of the polarisation. For this we use the fact that, while the polarisation of a photon is parallel transported along the photon geodesic, the infinitesimal shape of the source, e.g. its principal axis in the case of an ellipse, is Lie transported as described by the lens map. While at second order, the lens map usually contains a rotation, here we show that the presence of shear alone already induces an apparent rotation of the shape of an elliptical galaxy. As an example, we calculate the rotation of the shape vector with respect to the polarisation direction which is generated by a distribution of foreground Schwarzschild lenses. For radio galaxies, the intrinsic morphological orientation of a source and its polarised emission are correlated. It follows that observing both the polarisation and the morphological orientation provides information on both the unlensed source orientation and on the gravitational potential along the line of sight.
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López Ariste, A., B. Tessore, E. S. Carlín, Ph Mathias, A. Lèbre, J. Morin, P. Petit, M. Aurière, D. Gillet, and F. Herpin. "Asymmetric shocks in χ Cygni observed with linear spectropolarimetry." Astronomy & Astrophysics 632 (November 25, 2019): A30. http://dx.doi.org/10.1051/0004-6361/201936189.
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Aims. We derive information about the dynamics of the stellar photosphere, including pulsation, from a coherent interpretation of the linear polarisation detected in the spectral lines of the Mira star χ Cyg. Methods. From spectropolarimetric observations of χ Cyg, we performed a careful analysis of the polarisation signals observed in atomic and molecular lines, both in absorption and emission, using radiative transfer in the context of polarisation produced through two mechanisms: intrinsic polarisation and continuum depolarisation. We also explain the observed line doubling phenomenon in terms of an expanding shell in spherical geometry, which allows us to pinpoint the coordinates over the stellar disc with enhanced polarisation. Results. We find that the polarised spectrum of χ Cyg is dominated by intrinsic polarisation and has a negligible continuum depolarisation. The observed polarised signals can only be explained by assuming that this polarisation is locally enhanced by velocity fields. During the pulsation, radial velocities are not homogeneous over the disc. We map these regions of enhanced velocities. Conclusions. We set an algorithm to distinguish the origin of this polarisation in any stellar spectra of linear polarisation and to find a way to increase the signal by coherently adding many lines with an appropriated weight. Applied to the Mira star χ Cyg, we reached the unexpected result that during the pulsation, velocities are radial but not homogeneous over the disc. The reason for these local velocity enhancements are probably related to the interplay between the atmospheric pulsation dynamics and the underlying stellar convection.
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Landstreet, John D. "Basics of spectropolarimetry." Proceedings of the International Astronomical Union 9, S307 (June 2014): 311–20. http://dx.doi.org/10.1017/s1743921314007017.
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AbstractMany astronomical sources of radiation emit polarised radiation, for example because of the presence of a disk which produces linear polarisation by scattering some photospheric radiation, or because of the presence of a magnetic field, which leads to circular and sometimes linear polarisation of spectral line profiles. Measuring the wavelength dependence of the polarisation of radiation from such sources can reveal valuable and interesting constraints on the nature of the objects observed. This paper summarises the basic ideas of spectropolarimetry and describes some of the information it can provide.
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Khan, Pritam, Grace Brennan, James Lillis, Syed A. M. Tofail, Ning Liu, and Christophe Silien. "Characterisation and Manipulation of Polarisation Response in Plasmonic and Magneto-Plasmonic Nanostructures and Metamaterials." Symmetry 12, no. 8 (August 17, 2020): 1365. http://dx.doi.org/10.3390/sym12081365.
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Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the oscillation mode and the particle shape. Therefore, information on the polarisation properties of the LSPR scattering is crucial for identifying different oscillation modes within one particle and to distinguish differently shaped particles within one sample. On the contrary, the polarisation state of light itself can be arbitrarily manipulated by the inverse designed sample, known as metamaterials. Apart from polarisation state, external stimulus, e.g., magnetic field also controls the LSPR scattering from plasmonic nanostructures, giving rise to a new field of magneto-plasmonics. In this review, we pay special attention to polarisation and its effect in three contrasting aspects. First, tailoring between LSPR scattering and symmetry of plasmonic nanostructures, secondly, manipulating polarisation state through metamaterials and lastly, polarisation modulation in magneto-plasmonics. Finally, we will review recent progress in applications of plasmonic and magneto-plasmonic nanostructures and metamaterials in various fields.
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Gabuzda, Denise C. "Polarisation Characteristics and Variability of the Compact Radio Structures of AGN." Publications of the Astronomical Society of Australia 19, no. 1 (2002): 147–51. http://dx.doi.org/10.1071/as01099.
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AbstractVery long baseline interferometry (VLBI) polarisation measurements provide information about the parsec-scale magnetic field structures in compact active galactic nuclei (AGN), as well as the densities of relativistic and thermal electrons in the radio emitting regions. This paper reviews the role of polarisation VLBI in studies of AGN variability on both relatively long and short (intraday) timescales.
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Kochukhov, Oleg. "Multi-line techniques for inference of stellar magnetic fields." Proceedings of the International Astronomical Union 10, S305 (December 2014): 216–24. http://dx.doi.org/10.1017/s1743921315004809.
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AbstractSpectropolarimetric studies of stellar magnetic fields usually deal with extremely weak line polarisation signatures. The amplitudes of Stokes signals, even in magnetically sensitive spectral lines, are often well below the noise level realistically achievable with the current instrumentation. Consequently, a detection of these polarisation signatures and their meaningful analysis is impossible without combining information from multiple spectral lines. Here I review basic theoretical foundations of the multi-line spectropolarimetric diagnostic methods employed in stellar magnetometry, give examples of their application, and discuss recent efforts to interpret mean polarisation profiles with the help of detailed radiative transfer calculations.
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Liga, Gabriele, Astrid Barreiro, Hami Rabbani, and Alex Alvarado. "Extending Fibre Nonlinear Interference Power Modelling to Account for General Dual-Polarisation 4D Modulation Formats." Entropy 22, no. 11 (November 20, 2020): 1324. http://dx.doi.org/10.3390/e22111324.
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In optical communications, four-dimensional (4D) modulation formats encode information onto the quadrature components of two arbitrary orthogonal states of polarisation of the optical field. Many analytical models available in the optical communication literature allow, within a first-order perturbation framework, the computation of the average power of the nonlinear interference (NLI) accumulated in coherent fibre-optic transmission systems. However, all such models only operate under the assumption of transmitted polarisation-multiplexed two-dimensional (PM-2D) modulation formats, which only represent a limited subset of the possible dual-polarisation 4D (DP-4D) formats. Namely, only those where data transmitted on each polarisation channel are mutually independent and identically distributed. This paper presents a step-by-step mathematical derivation of the extension of existing NLI models to the class of arbitrary DP-4D modulation formats. In particular, the methodology adopted follows the one of the popular enhanced Gaussian noise model, albeit dropping most assumptions on the geometry and statistic of the transmitted 4D modulation format. The resulting expressions show that, whilst in the PM-2D case the NLI power depends only on different statistical high-order moments of each polarisation component, for a general DP-4D constellation, several other cross-polarisation correlations also need to be taken into account.
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Isabona, Joseph, Agbotiname Lucky Imoize, Paresh Rawat, Sajjad Shaukat Jamal, Bhasker Pant, Stephen Ojo, and Simon Karanja Hinga. "Realistic Prognostic Modeling of Specific Attenuation due to Rain at Microwave Frequency for Tropical Climate Region." Wireless Communications and Mobile Computing 2022 (April 14, 2022): 1–10. http://dx.doi.org/10.1155/2022/8209256.
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Absorption and scattering of propagated microwave radio signals by atmospheric variables, particularly rainfall, remained a major cause of propagation attenuation losses and service quality degradation over terrestrial communication links. The International Telecommunications Union Radio (ITU-R) reports and other related works in the literature provided information on attenuation due to rain and microwave propagation data. Such propagation attenuation information in the tropical region of Nigeria is destitute, especially at lower radio waves transmission frequencies. Therefore, this study addresses this problem by employing 12-year rainfall datasets to conduct realistic prognostic modeling of rain rate intensity levels. A classification of the rainfall data into three subgroups based on the depth of rainfall in the region is presented. Additionally, an in-depth estimation of specific rain attenuation intensities based on the 12-year rainfall data at 3.5 GHz is demonstrated. On average, the three rainfall classes produced rain rates of about 29.27 mm/hr, 73.71 mm/hr, and 105.39 mm/hr. The respective attenuation values are 0.89 dB, 1.71 dB, and 2.13 dB for the vertical polarisation and 1.09 dB, 1.20 dB, and 2.78 dB for the horizontal polarisation at 0.01% time percentage computation. Generally, results indicate that higher rain attenuation of 12% is observed for the horizontal polarisation compared to the vertical polarisation. These results can provide valuable first-hand information for microwave radio frequency planning in making appropriate decisions on attenuation levels due to different rainfall depths, especially for lower frequency arrays.
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Kang, Seogi, and Douglas W. Oldenburg. "Time domain electromagnetic‐induced polarisation: extracting more induced polarisation information from grounded source time domain electromagnetic data." Geophysical Prospecting 66, S1 (December 15, 2017): 74–86. http://dx.doi.org/10.1111/1365-2478.12600.
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Polyák, Gábor, Ágnes Urbán, and Petra Szávai. "Information Patterns and News Bubbles in Hungary." Media and Communication 10, no. 3 (August 31, 2022): 133–45. http://dx.doi.org/10.17645/mac.v10i3.5373.
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The study is based on data from a representative survey conducted in Hungary in 2020, which examined the public’s consumption of political and public information. Using the survey data, the authors attempt to map the consumption patterns of the Hungarian audience, with a special focus on the relationship between party preferences and the consumption of the various news sources with different ideological backgrounds. The research aims to better understand the phenomenon of polarisation, which is increasingly observed on both the supply and demand sides of the Hungarian news media. The focus of the study is to examine news consumption patterns in Hungary and the relationship between political polarisation and news consumption. The authors analysed the prevalence of information bubbles in the Hungarian public sphere, where consumers are only exposed to the views of one political side without being confronted with information or opinions that differ. Particular attention is paid to a special category of the Hungarian media system, the grey-zone media; they might seem to contribute greatly to the pluralism of the media system, but they are, in fact, strongly politically dependent. In addition to the identified news consumption patterns, the study aims to shed light on the importance and problematic nature of this grey-zone media category and to reveal how deeply the Hungarian public is actually dependent on the government.
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Sironi, G., E. Battistelli, G. Boella, F. Cavaliere, M. Gervasi, A. Passerini, D. Spiga, and M. Zannoni. "Polarimetry of the Cosmic Microwave Background from the Antarctic Plateau." Publications of the Astronomical Society of Australia 19, no. 3 (2002): 313–17. http://dx.doi.org/10.1071/as01074.
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AbstractDetection of linear polarisation at a level of 1 ppm or less, associated to the anisotropy of the cosmic microwave background, will confirm the cosmological origin of the observed anisotropy and provide information on the thermal history of the universe between the recombination epoch and now. In particular, detection of polarisation can help in deciding if the evolution of the universe included a reionisation epoch. We present the Mk3 model of our correlation polarimeter, an improved version of a system which has already been used for observations of the region of sky around the South Celestial Pole from Antarctica (in 1994 at Terra Nova Bay and in 1998 at Dome C).
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Eydam, Agnes, Gunnar Suchaneck, and Gerald Gerlach. "Characterisation of the polarisation state of embedded piezoelectric transducers by thermal waves and thermal pulses." Journal of Sensors and Sensor Systems 5, no. 1 (May 10, 2016): 165–70. http://dx.doi.org/10.5194/jsss-5-165-2016.
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Abstract. In this work, we apply the thermal wave method and the thermal pulse method for non-destructive characterisation of the polarisation state of embedded piezoelectric transducers. Heating the sample with a square-wave modulated laser beam or a single laser pulse leads to a pyroelectric current recorded in the frequency or time domain, respectively. It carries information about the polarisation state. Analytical and numerical finite element models describe the pyroelectric response of the piezoceramic. Modelling and experimental results are compared for a simple lead–zirconate–titanate (PZT) plate, a low-temperature co-fired ceramics (LTCC)/PZT sensor and actuator, and a macro-fibre composite (MFC) actuator.
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Gunnarsson Lorentzen, David. "Polarisation in political Twitter conversations." Aslib Journal of Information Management 66, no. 3 (May 19, 2014): 329–41. http://dx.doi.org/10.1108/ajim-09-2013-0086.
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Purpose – The purpose of this paper is to describe and analyse relationships and communication between Twitter actors in Swedish political conversations. More specifically, the paper aims to identify the most prominent actors, among these actors identify the sub-groups of actors with similar political affiliations, and describe and analyse the relationships and communication between these sub-groups. Design/methodology/approach – Data were collected during four weeks in September 2012, using Twitter API. The material included 77,436 tweets from 10,294 Twitter actors containing the hashtag #svpol. In total, 916 prominent actors were identified and categorised according to the main political blocks, using information from their profiles. Social network analysis was utilised to map the relationships and the communication between these actors. Findings – There was a marked dominance of the three main political blocks among the 916 most prominent actors: left block, centre-right block, and right-wing block. The results from the social network analysis suggest that while polarisation exists in both followership and re-tweet networks, actors follow and re-tweet actors from other groups. The mention network did not show any signs of polarisation. The blocks differed from each other with the right-wingers being tighter and far more active, but also more distant from the others in the followership network. Originality/value – While a few papers have studied political polarisation on Twitter, this is the first to study the phenomenon using followership data, mention data, and re-tweet data.
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Juvela, Mika, Vincent Guillet, Tie Liu, Isabelle Ristorcelli, Veli-Matti Pelkonen, Dana Alina, Leonardo Bronfman, et al. "Dust spectrum and polarisation at 850 μm in the massive IRDC G035.39-00.33." Astronomy & Astrophysics 620 (November 23, 2018): A26. http://dx.doi.org/10.1051/0004-6361/201833245.
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Context. The sub-millimetre polarisation of dust emission from star-forming clouds carries information on grain properties and on the effects that magnetic fields have on cloud evolution. Aims. Using observations of a dense filamentary cloud G035.39-00.33, we aim to characterise the dust emission properties and the variations of the polarisation fraction. Methods. JCMT SCUBA-2/POL-2 observations at 850 μm were combined with Planck 850 μm(353 GHz) data to map polarisation fraction at small and large scales. With previous total intensity SCUBA-2 observations (450 and 850 μm) and Herschel data, the column densities were determined via modified black-body fits and via radiative transfer modelling. Models were constructed to examine how the observed polarisation angles and fractions depend on potential magnetic field geometries and grain alignment processes. Results. POL-2 data show clear changes in the magnetic field orientation. These are not in contradiction with the uniform orientation and almost constant polarisation fraction seen by Planck, because of the difference in the beam sizes and the POL-2 data being affected by spatial filtering. The filament has a peak column density of N(H2) ~ 7 × 1022 cm−2, a minimum dust temperature of T ~ 12 K, and a mass of ~4300 M⊙ for the area N(H2) > 5 × 1021 cm−2. The estimated average value of the dust opacity spectral index is β ~ 1.9. The ratio of sub-millimetre and J-band optical depths is τ (250 μm)∕τ (J) ~ 2.5 × 10−3, more than four times the typical values for diffuse medium. The polarisation fraction decreases as a function of column density to p ~ 1% in the central filament. Because of noise, the observed decrease of p(N) is significant only at N(H2) > 2 × 1022 cm−2. The observations suggest that the grain alignment is not constant. Although the data can be explained with a complete loss of alignment at densities above ~104 cm−3 or using the predictions of radiative torques alignment, the uncertainty of the field geometry and the spatial filtering of the SCUBA-2 data prevent strong conclusions. Conclusions. The G035.39-00.33 filament shows strong signs of dust evolution and the low polarisation fraction is suggestive of a loss of polarised emission from its densest parts.
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Vandenbroucke, B., M. Baes, P. Camps, A. U. Kapoor, D. Barrientos, and J. P. Bernard. "Polarised emission from aligned dust grains in nearby galaxies: Predictions from the Auriga simulations." Astronomy & Astrophysics 653 (September 2021): A34. http://dx.doi.org/10.1051/0004-6361/202141333.
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Context. Polarised emission from non-spherical dust grains contains information about the alignment of these dust grains and traces the structure of the interstellar magnetic field. Methods. We post-processed a set of Milky-Way-like galaxies from the Auriga project, assuming a dust mix consisting of spheroidal dust grains that are partially aligned with the model magnetic field. We constrained our dust model using Planck 353 GHz observations of the Milky Way. This model was then extrapolated to shorter wavelengths that cover the peak of interstellar dust emission and to observations of arbitrarily oriented nearby Milky-Way-like galaxies. Results. Assuming an intrinsic linear polarisation fraction that does not vary significantly with wavelength for wavelengths longer than 50 micron, we predict a linear polarisation fraction with a maximum of 10 − 15% and a median value of ≈7% for face-on galaxies and ≈3% for edge-on galaxies. The polarisation fraction anti-correlates with the line of sight density and with the angular dispersion function which expresses the large-scale order of the magnetic field perpendicular to the line of sight. The maximum linear polarisation fraction agrees well with the intrinsic properties of the dust model. The true magnetic field orientation can be traced along low density lines of sight when it is coherent along the line of sight. These results also hold for nearby galaxies, where a coherent magnetic field structure is recovered over a range of different broad bands. Conclusions. Polarised emission from non-spherical dust grains accurately traces the large-scale structure of the galactic magnetic field in Milky-Way-like galaxies, with expected maximum linear polarisation fractions of 10 − 15%. To resolve this maximum, a spatial resolution of at least 1 kpc is required.
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Hasnan, Zahid. "The Politics of Service Delivery in Pakistan: Political Parties and the Incentives for Patronage, 1988-1999." Pakistan Development Review 47, no. 2 (June 1, 2008): 129–51. http://dx.doi.org/10.30541/v47i2pp.129-151.
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This paper examines the impact of the political party structure on the incentives for politicians to focus on patronage versus service delivery improvements in Pakistan. By analysing inter-provincial variations in the quality of service delivery in Pakistan, the paper argues that the more fragmented, factionalised, and polarised the party systems, the greater are the incentives for patronage, weakening service delivery improvements. Fragmentation and factionalism both exacerbate the information problems that voters have in assigning credit (blame) for service delivery improvements (deterioration), thereby creating the incentives for politicians to focus on targeted benefits. Polarisation, particularly ethnic polarisation, reduces the ability of groups to agree on the provision of public goods, again causing politicians to favour the delivery of targeted benefits.
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Scharien, R. K., J. Landy, and D. G. Barber. "First-year sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 1: In situ observations." Cryosphere 8, no. 6 (November 25, 2014): 2147–62. http://dx.doi.org/10.5194/tc-8-2147-2014.
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Abstract. Understanding the evolution of melt ponds on Arctic sea ice is important for climate model parameterisations, weather forecast models and process studies involving mass, energy and biogeochemical exchanges across the ocean–sea ice–atmosphere interface. A field campaign was conducted in a region of level first-year sea ice (FYI) in the central Canadian Arctic Archipelago (CAA), during the summer of 2012, to examine the potential for estimating melt pond fraction (fp) from satellite synthetic aperture radar (SAR). In this study, 5.5 GHz (C-band) dual co- (HH + VV – horizontal transmit and horizontal receive + vertical transmit and vertical receive) and cross-polarisation (HV + HH – horizontal transmit and vertical receive + horizontal transmit and horizontal receive) radar scatterometer measurements of melt-pond-covered FYI are combined with ice and pond properties to analyse the effects of in situ physical and morphological changes on backscatter parameters. Surface roughness statistics of ice and ponds are characterised and compared to the validity domains of the Bragg and integral equation model (IEM) scattering models. Experimental and model results are used to outline the potential and limitations of the co-polarisation ratio (VV / HH) for retrieving melt pond information, including fp, at large incidence angles (≥35°). Despite high variability in cross-polarisation ratio (HV / HH) magnitudes, increases at small incidence angles (<30°) are attributed to the formation of ice lids on ponds. Implications of the results for pond information retrievals from satellite C-, L- and P-band SARs are discussed.
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Torrente, Diego, Jordi Caïs, and Catalina Bolancé. "Economic crisis and social trust: Reviewing the effects of economic polarisation on social and institutional confidence." Social Science Information 58, no. 4 (December 2019): 631–59. http://dx.doi.org/10.1177/0539018419891321.
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The economic crisis of 2008 led to a significant erosion of trust in the countries that were hit hardest. However, whether this fall can best be explained by external economic factors or by the lack of response on the part of the institutions to civic needs and demands is unclear. This study uses the extreme case of Spain to bring new insights to this debate. Its aim is to analyse, in comparison with perceived institutional performance and other factors, the effect of increasing economic inequality and its polarisation on levels of social and institutional trust. The study examines the respective impact of these factors upon different social groups according to their degree of exposure to the effects of the crisis. It uses a simultaneous equations model to jointly examine interpersonal and institutional effects. Our results show that the social groups most severely affected by the recession lose a great deal of trust in others. We also find that polarisation of economic conditions has different effects depending on the institution. Institutional trust seems to vary according to the interest of different groups, but the economic position is an underlying factor, especially for specific segments of the population. Without calling into question the importance of institutional performance, our research sheds new light on the importance of economic polarisation and its joint impact on social and institutional trust. We suggest that, in severe economic recession scenarios, rising inequalities have a direct impact on the institutional trust of certain social groups and deteriorate a lot interpersonal confidence among the most disadvantaged.
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Graham, Stephen. "Bridging Urban Digital Divides? Urban Polarisation and Information and Communications Technologies (ICTs)." Urban Studies 39, no. 1 (January 2002): 33–56. http://dx.doi.org/10.1080/00420980220099050.
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Adil, Muhammad, Andrea Buono, Ferdinando Nunziata, Emanuele Ferrentino, Domenico Velotto, and Maurizio Migliaccio. "On the Effects of the Incidence Angle on the L-Band Multi-Polarisation Scattering of a Small Ship." Remote Sensing 14, no. 22 (November 17, 2022): 5813. http://dx.doi.org/10.3390/rs14225813.
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The monitoring of ships is of paramount importance for ocean and coastal area surveillance. The synthetic aperture radar is shown to be a key sensor to provide effective and continuous observation of ships due to its unique imaging capabilities. When advanced synthetic aperture radar imaging systems are considered, the full scattering information is available that was demonstrated to be beneficial in developing improved ship detection and classification algorithms. Nonetheless, the capability of polarimetric synthetic aperture radar to observe marine vessels is significantly affected by several imaging and environmental parameters, including the incidence angle. Nonetheless, how changes in the incidence angle affect the scattering of ships still needs to be further investigated since only a sparse analysis, i.e., on different kinds of ships of different sizes observed at multiple incidence angles, has been performed. Hence, in this study, for the first time, the polarimetric scattering of the same ship, i.e., a small fishing trawler, which is imaged multiple times under the same sea state conditions but in a wide range of incidence angles, is analysed. This unique opportunity is provided by a premium L-band UAVSAR airborne dataset that consists of five full-polarimetric synthetic aperture radar scenes collected in the Gulf of Mexico. Experimental results highlight the key role played by the incidence angle on both coherent, i.e., co-polarisation signature and pedestal height, and incoherent, i.e., multi-polarisation and total backscattering power, polarimetric scattering descriptors. Experimental results show that: (1) the polarised scattering component is more sensitive to the incidence angle with respect to the unpolarised one; (2) the co-polarised channel under horizontal polarisation dominated the polarimetric backscattering from the fishing trawler at lower angles of incidence, while both co-polarised channels contribute to the polarimetric backscattering at higher incidence angles; (3) the HV polarisation provides the largest target-to-clutter ratio at lower incidence angles, while the HH polarisation should be preferred at higher angles of incidence.
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Lestari, Anugrah Indah, and Dony Kushardono. "THE USE OF C-BAND SYNTHETIC APERTURE RADAR SATELLITE DATA FOR RICE PLANT GROWTH PHASE IDENTIFICATION." International Journal of Remote Sensing and Earth Sciences (IJReSES) 16, no. 1 (October 24, 2019): 31. http://dx.doi.org/10.30536/j.ijreses.2019.v16.a3171.
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Identification of the rice plant growth phase is an important step in estimating the harvest season and predicting rice production. It is undertaken to support the provision of information on national food availability. Indonesia’s high cloud coverage throughout the year means it is not possible to make optimal use of optical remote sensing satellite systems. However, the Synthetic Aperture Radar (SAR) remote sensing satellite system is a promising alternative technology for identifying the rice plant growth phase since it is not influenced by cloud cover and the weather. This study uses multi-temporal C-Band SAR satellite data for the period May–September 2016. VH and VV polarisation were observed to identify the rice plant growth phase of the Ciherang variety, which is commonly planted by farmers in West Java. Development of the rice plant growth phase model was optimized by obtaining samples spatially from a rice paddy block in PT Sang Hyang Seri, Subang, in order to acquire representative radar backscatter values from the SAR data on the age of certain rice plants. The Normalised Difference Polarisation Index (NDPI) and texture features, namely entropy, homogeneity and the Grey-Level Co-occurrence Matrix (GLCM) mean, were included as the samples. The results show that the radar backscatter value (σ0) of VH polarisation without the texture feature, with the entropy texture feature and GLCM mean texture feature respectively exhibit similar trends and demonstrate potential for use in identifying and monitoring the rice plant growth phase. The rice plant growth phase model without texture feature on VH polarisation is revealed as the most suitable model since it has the smallest average error.
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Kochukhov, O., M. Shultz, and C. Neiner. "Magnetic field topologies of the bright, weak-field Ap stars θ Aurigae andεUrsae Majoris." Astronomy & Astrophysics 621 (January 2019): A47. http://dx.doi.org/10.1051/0004-6361/201834279.
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Context.The brightest magnetic chemically peculiar stars θ Aur andεUMa were targeted by numerous studies of their photometric and spectroscopic variability. Detailed maps of chemical abundance spots were repeatedly derived for both stars. However, owing to the weakness of their surface magnetic fields, very little information on the magnetic field geometries of these stars is available.Aims.In this study we aim to determine detailed magnetic field topologies of θ Aur andεUMa based on modern, high-resolution spectropolarimetric observations.Methods.Both targets were observed in all four Stokes parameters using the Narval and ESPaDOnS spectropolarimeters. A multi-line technique of least-squares deconvolution was employed to detect polarisation signatures in spectral lines. These signatures were modelled with a Zeeman-Doppler imaging code.Results.We succeed in detecting variable circular and linear polarisation signatures for θ Aur. Only circular polarisation was detected forεUMa. We obtain new sets of high-precision longitudinal magnetic field measurements using mean circular polarisation metal line profiles as well as hydrogen line cores, which are consistent with historical data. Magnetic inversions revealed distorted dipolar geometries in both stars. The Fe and Cr abundance distributions, reconstructed simultaneously with magnetic mapping, do not show a clear correlation with the local magnetic field properties, with the exception of a relative element underabundance in the horizontal field regions along the magnetic equators.Conclusions.Our study provides the first ever detailed surface magnetic field maps for broad-line, weak-field chemically peculiar stars, showing that their field topologies are qualitatively similar to those found in stronger field stars. The Fe and Cr chemical abundance maps reconstructed for θ Aur andεUMa are at odds with the predictions of current theoretical atomic diffusion calculations.
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Braesemann, Fabian, Fabian Stephany, Ole Teutloff, Otto Kässi, Mark Graham, and Vili Lehdonvirta. "The global polarisation of remote work." PLOS ONE 17, no. 10 (October 20, 2022): e0274630. http://dx.doi.org/10.1371/journal.pone.0274630.
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The Covid-19 pandemic has led to the rise of digitally enabled remote work with consequences for the global division of labour. Remote work could connect labour markets, but it might also increase spatial polarisation. However, our understanding of the geographies of remote work is limited. Specifically, in how far could remote work connect employers and workers in different countries? Does it bring jobs to rural areas because of lower living costs, or does it concentrate in large cities? And how do skill requirements affect competition for employment and wages? We use data from a fully remote labour market—an online labour platform—to show that remote platform work is polarised along three dimensions. First, countries are globally divided: North American, European, and South Asian remote platform workers attract most jobs, while many Global South countries participate only marginally. Secondly, remote jobs are pulled to large cities; rural areas fall behind. Thirdly, remote work is polarised along the skill axis: workers with in-demand skills attract profitable jobs, while others face intense competition and obtain low wages. The findings suggest that agglomerative forces linked to the unequal spatial distribution of skills, human capital, and opportunities shape the global geography of remote work. These forces pull remote work to places with institutions that foster specialisation and complex economic activities, i. e. metropolitan areas focused on information and communication technologies. Locations without access to these enabling institutions—in many cases, rural areas—fall behind. To make remote work an effective tool for economic and rural development, it would need to be complemented by local skill-building, infrastructure investment, and labour market programmes.
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Weigand, M., and A. Kemna. "Debye decomposition of time-lapse spectral induced polarisation data." Computers & Geosciences 86 (January 2016): 34–45. http://dx.doi.org/10.1016/j.cageo.2015.09.021.
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Barnett, S. M. "Optical demonstrations of statistical decision theory for quantum systems." Quantum Information and Computation 4, no. 6&7 (December 2004): 450–59. http://dx.doi.org/10.26421/qic4.6-7-4.
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The work of Holevo and other pioneers of quantum information theory has given us limits on the performance of communication systems. Only recently, however, have we been able to perform laboratory demonstrations approaching the ideal quantum limit. This article presents some of the known limits and bounds together with the results of our experiments based on optical polarisation.
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Glazkov, A. V., I. K. Dzhioeva, D. V. Pervukhin, A. A. Pruchkina, and G. O. Rytikov. "Polarisation-optical model of a controlled random number generator." E-Management 4, no. 4 (January 28, 2022): 47–54. http://dx.doi.org/10.26425/2658-3445-2021-4-4-47-54.
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The subject of the paper is an original model of a tunable optical random number generator. The purpose of the article is to analyse the possibilities of using the proposed model to ensure the protection of the control signals in the projected telecommunication management system of the robotized agro-industrial complex of the Republic of South Ossetia.The research was carried out by methods of mathematical and information-logical modeling. The main results of the study are the information-logical model of the hardware implementation prototype, the descriptive mathematical model of its functioning and the obtained dependences of the quantitative characteristics of the generated random numbers statistical distributions on the main control parameter of the experimental setup.These results can be used in the design and the operation of the remote production facilities monitoring and management telecommunication systems’ components. The possibilities of prototype creating and functioning were demonstrated by visualising the schematic chart of the experimental equipment and by the quantitative estimates of “one” and “zero” signals observation probabilities under the different polarisation rotator orientations relative to the plane of the optical signals detecting system.
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Herranz, D., F. Argüeso, L. Toffolatti, A. Manjón-García, and M. López-Caniego. "A Bayesian method for point source polarisation estimation." Astronomy & Astrophysics 651 (July 2021): A24. http://dx.doi.org/10.1051/0004-6361/202039741.
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The estimation of the polarisation P of extragalactic compact sources in cosmic microwave background (CMB) images is a very important task in order to clean these images for cosmological purposes –for example, to constrain the tensor-to-scalar ratio of primordial fluctuations during inflation– and also to obtain relevant astrophysical information about the compact sources themselves in a frequency range, ν ∼ 10–200 GHz, where observations have only very recently started to become available. In this paper, we propose a Bayesian maximum a posteriori approach estimation scheme which incorporates prior information about the distribution of the polarisation fraction of extragalactic compact sources between 1 and 100 GHz. We apply this Bayesian scheme to white noise simulations and to more realistic simulations that include CMB intensity, Galactic foregrounds, and instrumental noise with the characteristics of the QUIJOTE (Q U I JOint TEnerife) experiment wide survey at 11 GHz. Using these simulations, we also compare our Bayesian method with the frequentist filtered fusion method that has been already used in the Wilkinson Microwave Anisotropy Probe data and in the Planck mission. We find that the Bayesian method allows us to decrease the threshold for a feasible estimation of P to levels below ∼100 mJy (as compared to ∼500 mJy which was the equivalent threshold for the frequentist filtered fusion). We compare the bias introduced by the Bayesian method and find it to be small in absolute terms. Finally, we test the robustness of the Bayesian estimator against uncertainties in the prior and in the flux density of the sources. We find that the Bayesian estimator is robust against moderate changes in the parameters of the prior and almost insensitive to realistic errors in the estimated photometry of the sources.
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Fasce, Angelo, Jesús Adrián-Ventura, and Diego Avendaño. "Do as the Romans do: On the authoritarian roots of pseudoscience." Public Understanding of Science 29, no. 6 (June 27, 2020): 597–613. http://dx.doi.org/10.1177/0963662520935078.
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Recent research highlights the implications of group dynamics in the acceptance and promotion of misconceptions, particularly in relation to the identity-protective attitudes that boost polarisation over scientific information. In this study, we successfully test a mediational model between right-wing authoritarianism and pseudoscientific beliefs. First, we carry out a comprehensive literature review on the socio-political background of pseudoscientific beliefs. Second, we conduct two studies ( n = 1189 and n = 1097) to confirm our working hypotheses: H1 – intercorrelation between pseudoscientific beliefs, authoritarianism and three axioms (reward for application, religiosity and fate control); H2 – authoritarianism and social axioms fully explain rightists’ proneness to pseudoscience; and H3 – the association between pseudoscience and authoritarianism is partially mediated by social axioms. Finally, we discuss our results in relation to their external validity regarding paranormal and conspiracy beliefs, as well as to their implications for group polarisation and science communication.
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Lenzi, Dominic. "Deliberating about Climate Change: The Case for ‘Thinking and Nudging’." Moral Philosophy and Politics 6, no. 2 (November 18, 2019): 313–36. http://dx.doi.org/10.1515/mopp-2018-0034.
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Abstract Proponents of deliberative democracy believe deliberation provides the best chance of finding effective and legitimate climate policies. However, in many societies there is substantial evidence of biased cognition and polarisation about climate change. Further, many appear unable to distinguish reliable scientific information from false claims or misinformation. While deliberation significantly reduces polarisation about climate change, and can even increase the provision of reliable beliefs, these benefits are difficult to scale up, and are slow to affect whole societies. In response, I propose a combined strategy of ‘thinking and nudging’. While deliberative theorists tend to view nudging askance, combining deliberation with nudges promises to be a timelier and more effective response to climate change than deliberation alone. I outline several proposals to improve societal deliberative capacity while reducing climate risks, including media reform, strategic communication and framing of debates, incentivising pro-climate behaviour change, and better education about science.
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Yang, Fengwei, Chandrasekhar Venkataraman, Sai Gu, Vanessa Styles, and Anotida Madzvamuse. "Force Estimation during Cell Migration Using Mathematical Modelling." Journal of Imaging 8, no. 7 (July 15, 2022): 199. http://dx.doi.org/10.3390/jimaging8070199.
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Cell migration is essential for physiological, pathological and biomedical processes such as, in embryogenesis, wound healing, immune response, cancer metastasis, tumour invasion and inflammation. In light of this, quantifying mechanical properties during the process of cell migration is of great interest in experimental sciences, yet few theoretical approaches in this direction have been studied. In this work, we propose a theoretical and computational approach based on the optimal control of geometric partial differential equations to estimate cell membrane forces associated with cell polarisation during migration. Specifically, cell membrane forces are inferred or estimated by fitting a mathematical model to a sequence of images, allowing us to capture dynamics of the cell migration. Our approach offers a robust and accurate framework to compute geometric mechanical membrane forces associated with cell polarisation during migration and also yields geometric information of independent interest, we illustrate one such example that involves quantifying cell proliferation levels which are associated with cell division, cell fusion or cell death.
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Tremblay, Steven E., Mengyao Xue, N. D. Ramesh Bhat, and Caterina Tiburzi. "Verifying the low frequency pulsar polarimetry of the MWA." Proceedings of the International Astronomical Union 13, S337 (September 2017): 416–17. http://dx.doi.org/10.1017/s174392131701033x.
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AbstractStudying the polarised properties of pulsars has a rich history giving unique geometric information about pulsars as well as testing the theories of pulsar emission physics. Performing such studies with the MWA has the attraction that the percentage of linear polarisation of many pulsars increases as the observing frequency decreases. Here we discuss the strategies being employed to verify the polarimetric response of the MWA’s high time resolution data.
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Kaiser, Florian, Panagiotis Vergyris, Anthony Martin, Djeylan Aktas, Marc P. De Micheli, Olivier Alibart, and Sébastien Tanzilli. "Quantum optical frequency up-conversion for polarisation entangled qubits: towards interconnected quantum information devices." Optics Express 27, no. 18 (August 26, 2019): 25603. http://dx.doi.org/10.1364/oe.27.025603.
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Hlatywayo, Dumisani John, and Emmanuel Sakala. "Resolving Optimum Magnetic Signatures for Drill-Hole Targeting in Gold Exploration – A Case Study for Mbudzane in Gwanda, Zimbabwe." International Journal of Geography and Geology 3, no. 1 (December 30, 2013): 9–29. http://dx.doi.org/10.18488/journal.10/2014.3.1/10.1.9.29.
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Optimum magnetic signatures for drill-hole targeting in gold exploration in Mbudzane were resolved from induced polarisation-resistivity and magnetic anomalies. Total magnetic field and a gold-in-soil map showed the area is magnetically quiet with high anomalous values along old gold workings. Induced polarisation was carried out along a grid for lines of 500m length, 50m separation and a baseline oriented at 330˚. The survey comprised a gradient array and three real sections. The magnetic survey was conducted over the same grid as the induced polarisation. Stations were set at 5m intervals for a line spacing of 50m. The results show intense anomalies that suggest different degrees of magnetic alteration and a set of conjugate lineaments and faults that possibly control the mineralisation in Mbudzane. The tilt derivative of the reduced-to-pole image resolves the separation between anomalies, giving information on the faulting. High chargeability is confined to the sheared and silicified mafic schist. The gradient resistivity image revealed contact between rock formations. Real section IP shows coincident low chargeability – low resistivity anomalies close to the surface. Chargeability intensity increases with depth, suggesting incipient development of disseminated sulphide replacement zones. A strong correlation between ground magnetic inferred contacts and apparent resistivity-chargeability anomalies forms the basis for suggesting a new drill-hole targeting. They dictate both the depth and angle at which drilling should be carried out. These results should be applicable to any region where drill-hole targeting in gold exploration may be required.
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Hendrick, N., and S. Hearn. "VECTOR WAVEFIELD-SEPARATION TECHNIQUES FOR IMPROVED MULTI-COMPONENT SEISMIC EXPLORATION." APPEA Journal 42, no. 1 (2002): 613. http://dx.doi.org/10.1071/aj01037.
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Analysis of multi-component seismic data commonly involves scalar processing of the vertical component to provide a conventional P-wave image, and scalar processing of the horizontal component(s) to yield an Swave image. A number of convincing examples now exist where such S-wave imagery has significantly enhanced hydrocarbon exploration.There is potential to achieve cleaner P- and S-wave images by more fully exploiting the true vector nature of multi-component reflection data. The simplest form of vector analysis, termed polarisation analysis, allows identification of different wave types. It does not, however, generally lead to effective wavefield separation, due to significant interference between the different waves in a typical exploration-seismic recording.More effective vector separation is possible if the particle-motion information from polarisation analysis is coupled with the more familiar tools of frequency and velocity filtering. Three related separation algorithms, termed MUSIC, IWSA and PIM are considered here. These techniques all utilise a parametric approach whereby wavefield slowness and polarisation are modelled simultaneously in the frequency domain.Synthetic and ocean-bottom cable examples are used to demonstrate practical issues relating to the use of these tools. The PIM algorithm is considered to be the most generally useful of the three multi-component wavefield separation algorithms. Implementation of these tools in a highly automated production environment is considered non-trivial. Hence, it is envisaged that such vector separation schemes will have most application for specialised data processing over identified target zones. Vector wavefield separation has the potential to amplify the considerable success already achieved with integrated P- and S-wave exploration.
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Marangotto, Daniele. "Extracting Maximum Information from Polarised Baryon Decays via Amplitude Analysis: The Λc+⟶pK−π+ Case." Advances in High Energy Physics 2020 (September 11, 2020): 1–20. http://dx.doi.org/10.1155/2020/7463073.
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We consider what is the maximum information measurable from the decay distributions of polarised baryon decays via amplitude analysis in the helicity formalism. We focus in particular on the analytical study of the Λc+⟶pK−π+ decay distributions, demonstrating that the full information on its decay amplitudes can be extracted from its distributions, allowing a simultaneous measurement of both helicity amplitudes and the polarisation vector. This opens the possibility to use the Λc+⟶pK−π+ decay for applications ranging from New Physics searches to low-energy QCD studies, in particular its use as absolute polarimeter for the Λc+ baryon. This result is valid as well for baryon decays having the same spin structure, and it is cross-checked numerically by means of a toy amplitude fit with Monte Carlo pseudodata.
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Schmidt, Sebastian, Christina Zorenböhmer, Dorian Arifi, and Bernd Resch. "Polarity-Based Sentiment Analysis of Georeferenced Tweets Related to the 2022 Twitter Acquisition." Information 14, no. 2 (January 27, 2023): 71. http://dx.doi.org/10.3390/info14020071.
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Twitter, one of the most important social media platforms, has been in the headlines regularly since its acquisition by Elon Musk in October 2022. This acquisition has had a strong impact on the employees, functionality, and discourse on Twitter. So far, however, there has been no analysis that examines the perception of the acquisition by the users on the platform itself. For this purpose, in this paper, we use georeferenced Tweets from the US and classify them using a polarity-based sentiment analysis. We find that the number of Tweets about Twitter and Elon Musk has increased significantly, as have negative sentiments on the subject. Using a spatial hot spot analysis, we find distinct centres of discourse, but no clear evidence of their significant change over time. On the West Coast, however, we suspect the first signs of polarisation, which could be an important indication for the future development of discourse on Twitter.
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Rosanov, N. N., I. A. Aleksandrov, M. V. Arkhipov, R. M. Arkhipov, I. Babushkin, N. A. Veretenov, A. V. Dadeko, D. A. Tumakov, and S. V. Fedorov. "Dissipative aspects of extreme nonlinear optics." Quantum Electronics 51, no. 11 (November 1, 2021): 959–69. http://dx.doi.org/10.1070/qel17637.
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Abstract Studies of extreme nonlinear optical effects, in which dissipative factors such as absorption and amplification of light in a medium play a fundamental role, are reviewed. The generation of pulses with extremely short duration down to unipolar ones is analysed by tracking the development of ideas related to the self-induced transparency phenomenon, whose practical application becomes real for extremely short pulses in lasers and laser media. Extreme radiation structuring is achieved in dissipative (laser) solitons characterised by a complex topology of phase and polarisation singularities, which is of interest for coding information.
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Sankaran, G. K., and J. G. Spandaw. "The moduli space of bilevel-6 abelian surfaces." Nagoya Mathematical Journal 168 (2002): 113–25. http://dx.doi.org/10.1017/s0027763000008394.
Full textAbstract:
AbstractWe show that the moduli space of abelian surfaces with polarisation of type (1,6) and a bilevel structure has positive Kodaira dimension and indeed pg ≥ 3. To do this we show that three of the Siegel cusp forms with character for the paramodular symplectic group constructed by Gritsenko and Nikulin are cusp forms without character for the modular group associated to this moduli problem. We then calculate the divisors of the corresponding differential forms, using information about the fixed loci of elements of the paramodular group previously obtained by Brasch.