Scale-discretised ridgelet transform on the sphere

We revisit the spherical Radon transform, also called the Funk-Radon transform, viewing it as an axisymmetric convolution on the sphere. Viewing the spherical Radon transform in this manner leads to a straightforward derivation of its spherical harmonic representation, from which we show the spherical Radon transform can be inverted exactly for signals exhibiting antipodal symmetry. We then construct a spherical ridgelet transform by composing the spherical Radon and scale-discretised wavelet transforms on the sphere. The resulting spherical ridgelet transform also admits exact inversion for antipodal signals. The restriction to antipodal signals is expected since the spherical Radon and ridgelet transforms themselves result in signals that exhibit antipodal symmetry. Our ridgelet transform is defined natively on the sphere, probes signal content globally along great circles, does not exhibit blocking artefacts, supports spin signals and exhibits an exact and explicit inverse transform. No alternative ridgelet construction on the sphere satisfies all of these properties. Our implementation of the spherical Radon and ridgelet transforms is made publicly available. Finally, we illustrate the effectiveness of spherical ridgelets for diffusion magnetic resonance imaging of white matter fibers in the brain.Comment: 5 pages, 4 figures, matches version accepted by EUSIPCO, code available at http://www.s2let.or

Fathers’ parenting, adverse life events, and adolescents’ emotional and eating disorder symptoms: the role of emotion regulation

Purpose: To investigate the role of emotion regulation in the relation between fathers’ parenting (specifically warmth, behavioral control and psychological control) and adolescents’ emotional and eating disorder symptoms, after adjustment for controls. Methods: A total of 203 11-18 year-old students from a school in a socio-economically disadvantaged area in North-East London completed questionnaires assessing emotional symptoms (measured with the Strengths and Difficulties Questionnaire’s (SDQ) Emotional Symptoms Scale), eating disorder symptoms (measured with the Eating Attitudes Test (EAT-26)), difficulties in emotion regulation (measured with the Difficulties in Emotion Regulation Scale (DERS)), and fathers’ overprotection and warmth, measured with the Parental Bonding Instrument (PBI), as well as behavioral and psychological control. The confounding variables considered were number of proximal (i.e., during the last year) adverse life events experienced, gender, age, and socio-economic status (eligibility for free school meals). Results: Adolescents’ difficulties in emotion regulation mediated the link between fathers’ psychological control and adolescents’ emotional symptoms, but not the link between fathers’ parenting and adolescents’ eating disorder symptoms, which appeared to be more directly linked to fathers’ psychological control and number of proximal adverse life events experienced. Proximal adverse life events experienced were also strongly associated with difficulties in emotion regulation. Conclusions: The study findings have implications for intervention programs which may prove more fruitful in addressing adolescent emotional problems by targeting underlying emotion regulation abilities, and in addressing adolescent eating disorder symptoms by protecting adolescents with a recent experience of multiple adverse life events. Parenting programs also stand to benefit from the evidence presented in this study that paternal psychological control may have uniquely harmful consequences for adolescent development through the hampering or atrophying of emotion regulation abilities and the encouragement of eating disorders

Sparse Image Reconstruction for the SPIDER Optical Interferometric Telescope

The concept of a recently proposed small-scale interferometric optical imaging device, an instrument known as the Segmented Planar Imaging Detector for Electro-optical Reconnaissance (SPIDER), is of great interest for its possible applications in astronomy and space science. Due to low weight, low power consumption, and high resolution, the SPIDER telescope could replace the large space telescopes that exist today. Unlike traditional optical interferometry the SPIDER accurately retrieves both phase and amplitude information, making the measurement process analogous to a radio interferometer. State of the art sparse radio interferometric image reconstruction techniques have been gaining traction in radio astronomy and reconstruct accurate images of the radio sky. In this work we describe algorithms from radio interferometric imaging and sparse image reconstruction and demonstrate their application to the SPIDER concept telescope through simulated observation and reconstruction of the optical sky. Such algorithms are important for providing high fidelity images from SPIDER observations, helping to power the SPIDER concept for scientific and astronomical analysis.Comment: 4 Pages, 2 Figures, 1 Tabl

From resource advantage to economic superiority : development and implications of China's rare earth policy

Rare Earth Elements (REE) have become the new strategic economic weapon for the modern age. Used in the manufacturing of products ranging from mobile phones to jet fighter engines, REEs have become the new “oil” of today in terms of economic and strategic importance. Currently, 95% of REEs mined globally are mined in China, giving China a monopoly on the industry. Deng Xiaoping foresaw the importance of REEs in 1992 when he commented: “as there is oil in the Middle East, there is rare earth in China.” Recently, China temporarily stopped exports of REEs to Japan, the EU and the US as an unofficial response to varying political and economic issues. This stoppage raised concerns as to the dependability of China and REE exports. Using the theory of neo-mercantilism, this paper analyzes China’s actions in the REE market and its subsequent economic and political implications. It concludes with a look at how countries are trying to position themselves away from a dependency on China