Optical Polarization M\"obius Strips and Points of Purely Transverse Spin Density

Tightly focused light beams can exhibit electric fields spinning around any axis including the one transverse to the beams' propagation direction. At certain focal positions, the corresponding local polarization ellipse can degenerate into a perfect circle, representing a point of circular polarization, or C-point. We consider the most fundamental case of a linearly polarized Gaussian beam, where - upon tight focusing - those C-points created by transversely spinning fields can form the center of 3D optical polarization topologies when choosing the plane of observation appropriately. Due to the high symmetry of the focal field, these polarization topologies exhibit non trivial structures similar to M\"obius strips. We use a direct physical measure to find C-points with an arbitrarily oriented spinning axis of the electric field and experimentally investigate the fully three-dimensional polarization topologies surrounding these C-points by exploiting an amplitude and phase reconstruction technique.Comment: 5 pages, 3 figures; additional supplementary materials with 4 pages, 3 figure

The magnetic and electric transverse spin density of spatially confined light

When a beam of light is laterally confined, its field distribution can exhibit points where the local magnetic and electric field vectors spin in a plane containing the propagation direction of the electromagnetic wave. The phenomenon indicates the presence of a non-zero transverse spin density. Here, we experimentally investigate this transverse spin density of both magnetic and electric fields, occurring in highly-confined structured fields of light. Our scheme relies on the utilization of a high-refractive-index nano-particle as local field probe, exhibiting magnetic and electric dipole resonances in the visible spectral range. Because of the directional emission of dipole moments which spin around an axis parallel to a nearby dielectric interface, such a probe particle is capable of locally sensing the magnetic and electric transverse spin density of a tightly focused beam impinging under normal incidence with respect to said interface. We exploit the achieved experimental results to emphasize the difference between magnetic and electric transverse spin densities.Comment: 7 pages, 4 figure

Evaluating the genetic progress of wheat in NSW, 1992-2009

Intellectual Property Regimes (IPRs) have been justified on the basis that they promote innovation, but it is not always clear that they do so. Empirical studies of IPRs in an Australian context have been limited. Plant variety protection is one form of IPR. The passing of the Australian Plant Breeder’s Rights Act of 1994 has been followed by significant commercialisation of the wheat breeding industry. The purpose of this paper is to consider whether this commercialisation has benefited wheat productivity through varietal improvement. We estimate a linear crop production function, using a random effects Hausman Taylor estimator to evaluate differences in genetic contributions to productivity between public and private wheat varieties commercially released in NSW over the period 1992-2009 using crop varietal data. Results from the Hausman Taylor estimator show that private varieties, on average, have outperformed public varieties over the period, suggesting that Plant Breeder’s Rights has promoted productive innovation in wheat. However, when we consider the best performing genetics of the varieties, public varieties have, in some years, outperformed privately bred varieties.genetic change, technical change, innovation, wheat breeding, intellectual property, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Reflections on the design of HappyHere, a digital installation facilitating participation, reflection and discussion on wellbeing data in the Arts sector.

In the Arts sector there is increasing interest in the relationship between art and wellbeing. In this paper, we present research exploring the ways in which HappyHere engaged participants to reflect on and discuss wellbeing while visiting a leading art gallery. We describe the design of HappyHere and explain how tangible interactions in a community space can provide a novel approach for engaging participants and gathering data to enable the evaluation of mental wellbeing in museums and galleries. Finally, we reflect on qualitative research with participants and volunteers throughout the twelve-week deployment of the project. This paper disseminates the design process to allow Human-Computer Interaction (HCI) researchers to deploy similar digital installations in new environments and establishes insights to inform the development of future tangible wellbeing research studies in the Arts and wider community, benefitting HCI researchers, arts professionals, healthcare practitioners and visitors to arts organisations

Reflections on the design of HappyHere, a digital installation facilitating participation, reflection and discussion on wellbeing data in the Arts sector.

In the Arts sector there is increasing interest in the relationship between art and wellbeing. In this paper, we present research exploring the ways in which HappyHere engaged participants to reflect on and discuss wellbeing while visiting a leading art gallery. We describe the design of HappyHere and explain how tangible interactions in a community space can provide a novel approach for engaging participants and gathering data to enable the evaluation of mental wellbeing in museums and galleries. Finally, we reflect on qualitative research with participants and volunteers throughout the twelve-week deployment of the project. This paper disseminates the design process to allow Human-Computer Interaction (HCI) researchers to deploy similar digital installations in new environments and establishes insights to inform the development of future tangible wellbeing research studies in the Arts and wider community, benefitting HCI researchers, arts professionals, healthcare practitioners and visitors to arts organisations

Do Childhood Vaccines Have Non-Specific Effects on Mortality

A recent article by Kristensen et al. suggested that measles vaccine and bacille Calmette–Guérin (BCG) vaccine might\ud reduce mortality beyond what is expected simply from protection against measles and tuberculosis. Previous reviews of the potential effects of childhood vaccines on mortality have not considered methodological features of reviewed studies. Methodological considerations play an especially important role in observational assessments, in which selection factors for vaccination may be difficult to ascertain. We reviewed 782 English language articles on vaccines and childhood mortality and found only a few whose design met the criteria for methodological rigor. The data reviewed suggest that measles vaccine delivers its promised reduction in mortality, but there is insufficient evidence to suggest a mortality benefit above that caused by its effect on measles disease and its sequelae. Our review of the available data in the literature reinforces how difficult answering these considerations has been and how important study design will be in determining the effect of specific vaccines on all-cause mortality.\u