Nanophotonics for dark materials, filters, and optical magnetism

Research on nanophotonic structures for three application areas is described, a near perfect optical absorber based on a graphene/dielectric stack, an ultraviolet bandpass filter formed with an aluminum/dielectric stack, and structures exhibiting homogenizable magnetic properties at infrared frequencies. The graphene stack can be treated as a effective, homogenized medium that can be designed to reflect little light and absorb an astoundingly high amount per unit thickness, making it an ideal dark material and providing a new avenue for photonic devices based on two-dimensional materials. Another material stack arrangement with thin layers of metal and insulator forms a multi-cavity filter that can effectively act as an ultraviolet filter without the usual sensitivity of the incident angle of the light. This is important in sensing applications where the visible part of the spectrum is to be removed, allowing detection of ultraviolet signals. Finally, achieving a magnetic material that functions at optical frequencies would be of enormous scientific and technological impact, including for imaging, sensing and optical storage applications. The challenge has been to find a guiding principle and a suitable arrangement of constituent materials. A lattice of dielectric spheres is shown to provide a legitimately homogenized material with a magnetic response. This should pave the way for experimental studies. More specifically, a graphene stack is designed, fabricated and characterized. The structure shows strong absorption of light. Spectroscopic ellipsometry is used to obtain the complex sheet conductivity of graphene. Further modeling results establish the graphene stack as the darkest optical material, with lower reflectivity and higher per-unit-length absorption than alternative light-absorbing materials. An optical bandpass filter based on a metal/dielectric structure is modeled, showing performance that is largely independent of the angle of incidence. Parametric evaluations of the reflection phase shift at the metal-dielectric interface provide insight and design information. Filter passbands in the ultraviolet (UV) through visible or longer wavelengths can be achieved by engineering the dielectric thickness and selecting a metal with an appropriate plasma frequency, as demonstrated in simulations. A lattice of suitable dielectric particles is shown to fulfill the requirements for a magnetic optical material. Using Mie theory, the microscopic origin of the magnetic response is explicitly identified as being due to the magnetic dipole resonance of an isolated sphere. This provides a design basis, and dielectric and lattice requirements with candidate dielectrics that will allow magnetic materials to be designed and fabricated for optical applications are presented

The ideological basis of antiscientific attitudes: Effects of authoritarianism, conservatism, religiosity, social dominance, and system justification

Serious concerns about public distrust of scientific experts and the spread of misinformation are growing in the US and elsewhere. To gauge ideological and psychological variability in attitudes toward science, we conducted an extensive analysis of public opinion data based on a nationally representative survey of U.S. adults ( N = 1,500) and a large replication sample ( N = 2,119). We estimated the unique effects of partisanship, symbolic and operational forms of political ideology, right-wing authoritarianism (RWA), social dominance orientation (SDO), and general system justification (GSJ), after adjusting for demographic factors. Multiverse analyses revealed that (a) conservatism and SDO were significant predictors of distrust of climate science in > 99.9% of model specifications, with conservatism accounting for 80% of the total variance; (b) conservatism, RWA, religiosity, (male) sex, (low) education, (low) income, and distrust of climate science were significant predictors of skepticism about science in general (vs. faith) in > 99.9% of model specifications; (c) conservatism, RWA, (low) education, and distrust of climate science were significant predictors of trust in ordinary people (over scientific experts) > 99.9% of the time; and (d) GSJ was a significant predictor of trust in scientific experts (over ordinary people) 81% of the time, after adjusting for all other demographic and ideological factors. Implications for the role of science in democratic society are discussed

The challenges of urban ageing : making cities age-friendly in Europe

Urban ageing is an emerging domain that deals with the population of older people living in cities. The ageing of society is a positive yet challenging phenomenon, as population ageing and urbanisation are the culmination of successful human development. One could argue whether the city environment is an ideal place for people to grow old and live at an old age compared to rural areas. This viewpoint article explores and describes the challenges that are encountered when making cities age-friendly in Europe. Such challenges include the creation of inclusive neighbourhoods and the implementation of technology for ageing-in-place. Examples from projects in two age-friendly cities in The Netherlands (The Hague) and Poland (Cracow) are shown to illustrate the potential of making cities more tuned to the needs of older people and identify important challenges for the next couple of years. Overall, the global ageing of urban populations calls for more age-friendly approaches to be implemented in our cities. It is a challenge to prepare for these developments in such a way that both current and future generations of older people can benefit from age-friendly strategies

Amygdala structure and the tendency to perceive the social system as legitimate and desirable

Individual variation in preferences to maintain vs. change the societal status quo can play out in the political realm by choosing leaders and policies that reinforce or undermine existing inequalities. We sought to understand which individuals are likely to defend or challenge inequality in society by exploring the neuroanatomical substrates of system justification tendencies. In two independent neuroimaging studies, we observed that larger bilateral amygdala volume was positively correlated with the tendency to believe that the existing social order was legitimate and desirable. These results held for members of advantaged and disadvantaged groups (men and women). Furthermore, individuals with larger amygdala volume were less likely to participate in subsequent protest movements. We ruled out alternative explanations in terms of attitudinal extremity and political orientation per se. Exploratory whole brain analyses suggested that system justification effects may extend to structures adjacent to the amygdala, including parts of the insula and orbitofrontal cortex. These findings suggest that the amygdala may provide a neural substrate for maintaining the status quo, and opens avenues for further investigation linking system justification and other neuroanatomical regions

Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3

We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.Comment: 6 pages, 4 figure

On the monodromy of the moduli space of Calabi-Yau threefolds coming from eight planes in P3\mathbb{P}^3

It is a fundamental problem in geometry to decide which moduli spaces of polarized algebraic varieties are embedded by their period maps as Zariski open subsets of locally Hermitian symmetric domains. In the present work we prove that the moduli space of Calabi-Yau threefolds coming from eight planes in $\mathbb{P}^3$ does {\em not} have this property. We show furthermore that the monodromy group of a good family is Zariski dense in the corresponding symplectic group. Moreover, we study a natural sublocus which we call hyperelliptic locus, over which the variation of Hodge structures is naturally isomorphic to wedge product of a variation of Hodge structures of weight one. It turns out the hyperelliptic locus does not extend to a Shimura subvariety of type III (Siegel space) within the moduli space. Besides general Hodge theory, representation theory and computational commutative algebra, one of the proofs depends on a new result on the tensor product decomposition of complex polarized variations of Hodge structures.Comment: 26 page

Neither fair nor unchangeable but part of the natural order: orientations towards inequality in the face of criticism of the economic system

The magnitude of climate change threats to life on the planet is not matched by the level of current mitigation strategies. To contribute to our understanding of inaction in the face of climate change, the reported study draws upon the pro status quo motivations encapsulated within System Justification Theory. In an online questionnaire study, participants (N = 136) initially completed a measure of General System Justification. Participants in a “System-critical” condition were then exposed to information linking environmental problems to the current economic system; participants in a Control condition were exposed to information unrelated to either environmental problems or the economic system. A measure of Economic System Justification was subsequently administered. Regressions of Economic System Justification revealed interactions between General System Justification and Information Type: higher general system justifiers in the System-critical condition rated the economic system as less fair than did their counterparts in the Control condition. However, they also indicated inequality as more natural than did their counterparts in the Control condition. The groups did not differ in terms of beliefs about the economic system being open to change. The results are discussed in terms of how reassurance about the maintenance of the status quo may be bolstered by recourse to beliefs in a natural order

The 12 Item Social and Economic Conservatism Scale (SECS)

Recent years have seen a surge in psychological research on the relationship between political ideology (particularly conservatism) and cognition, affect, behaviour, and even biology. Despite this flurry of investigation, however, there is as yet no accepted, validated, and widely used multi-item scale of conservatism that is concise, that is modern in its conceptualisation, and that includes both social and economic conservatism subscales. In this paper the 12-Item Social and Economic Conservatism Scale (SECS) is proposed and validated to help fill this gap. The SECS is suggested to be an important and useful tool for researchers working in political psychology

The persistent cosmic web and its filamentary structure I: Theory and implementation

We present DisPerSE, a novel approach to the coherent multi-scale identification of all types of astrophysical structures, and in particular the filaments, in the large scale distribution of matter in the Universe. This method and corresponding piece of software allows a genuinely scale free and parameter free identification of the voids, walls, filaments, clusters and their configuration within the cosmic web, directly from the discrete distribution of particles in N-body simulations or galaxies in sparse observational catalogues. To achieve that goal, the method works directly over the Delaunay tessellation of the discrete sample and uses the DTFE density computed at each tracer particle; no further sampling, smoothing or processing of the density field is required. The idea is based on recent advances in distinct sub-domains of computational topology, which allows a rigorous application of topological principles to astrophysical data sets, taking into account uncertainties and Poisson noise. Practically, the user can define a given persistence level in terms of robustness with respect to noise (defined as a "number of sigmas") and the algorithm returns the structures with the corresponding significance as sets of critical points, lines, surfaces and volumes corresponding to the clusters, filaments, walls and voids; filaments, connected at cluster nodes, crawling along the edges of walls bounding the voids. The method is also interesting as it allows for a robust quantification of the topological properties of a discrete distribution in terms of Betti numbers or Euler characteristics, without having to resort to smoothing or having to define a particular scale. In this paper, we introduce the necessary mathematical background and describe the method and implementation, while we address the application to 3D simulated and observed data sets to the companion paper.Comment: A higher resolution version is available at http://www.iap.fr/users/sousbie together with complementary material. Submitted to MNRA