Angle diversity to increase coverage and position accuracy in 3D visible light positioning

The most common approach to light-based indoor positioning relies on multilateration of received signals to the mobile device. Any deficiencies in the fidelity of these light signals can significantly distort position estimates. In this paper, we propose a method to dynamically control the light distribution from the overhead luminaires to mitigate fading effects that would otherwise occur under static lighting. By manipulating the direction of the luminaire, effectively the dispersion pattern, we introduce signal diversity in the form of multiple pointing angles and light distributions. In addition to providing angle diversity, steering and then tracking sustains the maximal line-of-sight path between a source and receiver, which reduces angle-dependent attenuation and optimizes the signal-to-noise ratio for any coordinate without needing to change the physical properties of the source or receiver. This gain in signal strength combats the limited field-of-view of luminaires and photodiodes to provide better overall coverage, which translates directly to increase positioning accuracy, particularly in a 3D space. In the results, we show field-of-view gains of 43% and improvements in MSE of 20cm.Accepted manuscrip

Beyond identity: Membership norms and regional organization

What is a region and how can we best understand a state’s eligibility for membership in a regional political community? Scholars have sought to answer these questions in terms of geographic proximity and social-psychological identity, but neither concept can accommodate the contestation and change that characterize the social construction of regions. Instead, this article argues that the limits of regions are defined within regional organizations by member states’ governments plus supranational actors deliberating over a common definition of the characteristics that members and potential members are expected to share. The concept of membership norms thus offers powerful insights into how regional communities define who is eligible for membership, how these definitions change over time and the incentives they create for those seeking to promote or block an applicant state. The evolution of the European Union’s membership norms since the 1950s illustrates this argument.Article / Letter to edito

Indoor 3D localization with low-cost LiFi components

Indoor positioning or localization is an enabling technology expected to have a profound impact on mobile applications. Various modalities of radio frequency, ultrasound, and light can be used for localization; in this paper we consider how visible light positioning can be realized for 3D positioning as a service comprised of optical sources as part of an overarching lighting infrastructure. Our approach, called Ray-Surface Positioning, uses one or more overhead luminaires, modulated as LiFi, and is used in conjunction with a steerable laser to realize position estimates in three dimensions. In this paper, we build and demonstrate Ray-Surface Positioning using low-cost commodity components in a test apparatus representing one quadrant of a 4m × 4m × 1m volume. Data are collected at regular intervals in the test volume representing 3D position estimates and is validated using a motion capture system. For the low-cost components used, results show position estimate errors of less than 30cm for 95% of the test volume. These results, generated with commodity components, show the potential for 3D positioning in the general case. When the plane of the receiver is known a priori, the position estimate error diminishes to the resolution of the steering mechanism.Accepted manuscrip

Structure of cellulose microfibrils in primary cell-walls from collenchyma

In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production

Renewing the Exploration Approach for Mid-Enthalpy Systems: Examples from Northern England and Scotland

After a promising start in the 1970s and 80s, the UK rather fell behind other countries in the search for viable mid-enthalpy geothermal resources. This situation began to turn around in 2004, when the first of three deep geothermal exploration boreholes were drilled in northern England. What distinguished these from earlier drilling in Cornwall was the deliberate search for naturallyhigh permeability associated with major faults, especially those that have undergone strike-slip reactivation during the Cenozoic. Boreholes at Eastgate in the North Pennines targeted buried radiothermal granite, whereas the 1,821m-deep Science Central Borehole in Newcastle upon Tyne targeted a postulated deep sedimentary aquifer (the Fell Sandstones), which were inferred to be connected laterally to the granitic heat source by a major fault (the reactivation of the Iapetus geo-suture). The drilling was in both cases rewarded with impressive heat flows, and in the case of Eastgate with what is believed to be the highest permeability yet found in a deep granite batholith anywhere in the world. In parallel with these developments, a re-assessment was made of the preexisting geothermal heat flow database for the UK, applying newly-standardised correction protocols for palaeoclimatic and topographic distortions, which were found to be particularly marked in Scotland (where only shallow boreholes had been used to establish geothermal gradients in the original 1980s analysis), Similar prospects in northern England (similar to that drilled at Science Central) are now the focus of commercial exploration efforts. Appraisal of fault dispositions relative to the present-day maximum compressive stress azimuth are being used to identify the most promising areas for intersecting fault-related permeability at depth. New geophysical tools – most notably atomic dielectric resonance scanning – are also being appraised for their ability to directly detect features (such as hot brines) which are indicative of localised convection in target fault zones and aquifers

Beyond identity: Membership norms and regional organization

What is a region and how can we best understand a state’s eligibility for membership in a regional political community? Scholars have sought to answer these questions in terms of geographic proximity and social-psychological identity, but neither concept can accommodate the contestation and change that characterize the social construction of regions. Instead, this article argues that the limits of regions are defined within regional organizations by member states’ governments plus supranational actors deliberating over a common definition of the characteristics that members and potential members are expected to share. The concept of membership norms thus offers powerful insights into how regional communities define who is eligible for membership, how these definitions change over time and the incentives they create for those seeking to promote or block an applicant state. The evolution of the European Union’s membership norms since the 1950s illustrates this argument.The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020

The Bailey Point Region and Other Muskox Refugia in the Canadian Arctic: A Short Review

The muskox (Ovibos moschatus) is widely distributed over much of arctic Canada but only at a few locations do their densities remain high and populations relatively stable. These refugia constitute the most favourable muskox ranges in the Canadian Arctic Archipelago .... Refugia for muskoxen in the High Arctic include lowlands on eastern Axel Heiberg Island in the Mokka Fiord region, the lowlands of northeastern Devon Island, and the Bailey Point region of Melville Island .... All of those regions historically have supported high densities of muskoxen from time to time but the Bailey Point region must be considered the best habitat for muskoxen in the Canadian High Arctic. ..