Use of orbiting reflectors to decrease the technological challenges of surviving the lunar night

In this paper the feasibility of using lunar reflectors to decrease the technological challenges of surviving the lunar night is investigated. This is achieved by attempting to find orbits in the two-body problem where the argument of periapsis is constantly Sun-pointing to maximise the time spent by the reflectors over the night-side of the Moon. Using these orbits the ability of reflectors of varying sizes to provide sufficient illumination to a target point on the surface is determined for scenarios where a latitude band is constantly illuminated and a scenario where a specific point is tracked. The optimum masses required for these far-term scenarios are large. However, a nearer-term scenario using low altitude orbits suggest that the effective duration of the lunar night can be reduced by up to 50% using a set of 300 parabolic reflectors of 100m radius with a total system mass of 370 tonnes. A system is also demonstrated that will allow a partial illumination of the craters in the Moon’s polar region for a mass up to 700kg

Geo-engineering using dust grains in heliotropic elliptical orbits

This paper examines the concept of a Saturn-like Earth ring comprised of dust grains to offset global warming. A new family of non-Keplerian periodic orbits, under the effects of solar radiation pressure and the Earth’s oblateness J2 perturbation, is selected to increase the lifetime of the passive cloud of particles and, thus, increase the efficiency of this geo-engineering strategy. An analytical model is used to predict the evolution of the dust due to solar-radiation pressure and the J2 effect. The attenuation of the solar radiation can then be calculated from the ring model. In comparison to circular orbits, eccentric orbits yield a more stable environment for small grain sizes and therefore achieve higher efficiencies when the orbital decay of the material is considered. Moreover, the special orbital dynamics experienced by high area-to-mass ratio objects, influenced by solar radiation pressure and the J2 effect, ensure the ring will maintain a permanent heliotropic shape, with dust spending the largest portion of time on the Sun facing side. It is envisaged that small dust grains can be released with an initial Δv to enter an eccentric orbit with Sun-facing apogee. Finally, an estimate of 5.94x1011 kg is computed as the total mass required to offset the effects of global warming

The feasibility of using an L1 positioned dust cloud as a method of space-based geoengineering

In this paper a method of geoengineering is proposed involving clouds of dust placed in the vicinity of the L1 point as an alternative to the use of thin film reflectors. The aim of this scheme is to reduce the manufacturing requirement for space-based geoengineering. It has been concluded that the mass requirement for a cloud placed at the classical L1 point, to create an average solar insolation reduction of 1.7%, is 7.60x1010 kg yr−1 whilst a cloud placed at a displaced equilibrium point created by the inclusion of the effect of solar radiation pressure is 1.87x1010 kg yr−1. These mass ejection rates are considerably less than the mass required in other unprocessed dust cloud methods proposed and are comparable to thin film reflector geoengineering requirements. Importantly, unprocessed dust sourced in-situ is seen as an attractive scheme compared to highly engineered thin film reflectors. It is envisaged that the required mass of dust can be extracted from captured near Earth asteroids, whilst stabilised in the required position using the impulse provided by solar collectors or mass drivers used to eject material from the asteroid surface

Activism, arenas and accounts in conflicts over tobacco control

Purpose - The purpose of this paper is to provide theoretical and empirical insights into the effective use of external accounts by social activists in conflict arenas in order to bring about change. Design/methodology/approach - This paper presents a longitudinal case study of Action on Smoking and Health UK (ASH) and their use of external accounts and other activist practices during the period 1999-2010. The authors explore these practices from the perspective of one organisation engaged in conflict arenas concerning the (un)acceptability of tobacco production, consumption and governance. The authors conduct the exploration based upon a dynamic conflict arena framework that attends to the range of external accounting and activist practices, tactical intentions and states of conflict used by ASH to confront the tobacco industry and bring about change in tobacco governance. Findings - The study identifies the use of a diverse range of external accounts and other activist practices. This assemblage of practices was used to confront, counter-act and to co-operate with actors engaged in tobacco-related conflicts. The evidence suggests that the deployment of different types of external accounts by ASH was aligned to the context of the particular conflict arena involved, and was influenced by the strategy and engagement tactics of the activists and other actors, as well as power dynamics and acceptability of the tobacco governance in the conflict arena. Whilst ASH used different external accounts in specific episodes of activism, these individual accounts also contributed to an emerging holistic account of the unacceptable consequences of tobacco production, consumption and governance. Originality/value - This study provides new theoretical and empirical insights into how external accounts can contribute to the problematisation of governance and development of social and environmental change agendas. The dynamic conflict arena framework developed in this paper creates new visibilities and possibilities for developing external accounting practices and for researching this fast-developing area of social and environmental accounting.PostprintPeer reviewe

Kinetic and sequence-structure-function analysis of known LinA variants with different hexachlorocyclohexane isomers

BACKGROUND Here we report specific activities of all seven naturally occurring LinA variants towards three different isomers, α, γ and δ, of a priority persistent pollutant, hexachlorocyclohexane (HCH). Sequence-structure-function differences contributing to the differences in their stereospecificity for α-, γ-, and δ-HCH and enantiospecificity for (+)- and (-)-α -HCH are also discussed. METHODOLOGY/PRINCIPAL FINDINGS Enzyme kinetic studies were performed with purified LinA variants. Models of LinA2(B90A) A110T, A111C, A110T/A111C and LinA1(B90A) were constructed using the FoldX computer algorithm. Turnover rates (min(-1)) showed that the LinAs exhibited differential substrate affinity amongst the four HCH isomers tested. α-HCH was found to be the most preferred substrate by all LinA's, followed by the γ and then δ isomer. CONCLUSIONS/SIGNIFICANCE The kinetic observations suggest that LinA-γ1-7 is the best variant for developing an enzyme-based bioremediation technology for HCH. The majority of the sequence variation in the various linA genes that have been isolated is not neutral, but alters the enantio- and stereoselectivity of the encoded proteins.This work was supported by the Indo-Australian Biotechnology Fund from the Department of Education Science and Technology (DEST), Australia and the Department of Biotechnology (DBT), India

The impact of targeting all elderly persons in England and Wales for yearly influenza vaccination: excess mortality due to pneumonia or influenza and time trend study.

OBJECTIVE: To investigate the impact on mortality due to pneumonia or influenza of the change from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales. DESIGN: Excess mortality estimated using time series of deaths registered to pneumonia or influenza, accounting for seasonality, trend and artefacts. Non-excess mortality plotted as proxy for long-term trend in mortality. SETTING: England and Wales. PARTICIPANTS: Persons aged 65-74 and 75+ years whose deaths were registered to underlying pneumonia or influenza between 1975/1976 and 2004/2005. OUTCOME MEASURES: Multiplicative effect on average excess pneumonia and influenza deaths each winter in the 4-6 winters since age group-based targeting of vaccination was introduced (in persons aged 75+ years from 1998/1999; in persons aged 65+ years from 2000/2001), estimated using multivariable regression adjusted for temperature, antigenic drift and vaccine mismatch, and stratified by dominant circulating influenza subtype. Trend in baseline weekly pneumonia and influenza death rates. RESULTS: There is a suggestion of lower average excess mortality in the six winters after age group-based targeting began compared to before, but the CI for the 65-74 years age group includes no difference. Trend in baseline pneumonia and influenza mortality shows an apparent downward turning point around 2000 for the 65-74 years age group and from the mid-1990s in the 75+ years age group. CONCLUSIONS: There is weakly supportive evidence that the marked increases in vaccine coverage accompanying the switch from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales were associated with lower levels of pneumonia and influenza mortality in older people in the first 6 years after age group-based targeting began. The possible impact of these policy changes is observed as weak evidence for lower average excess mortality as well as a turning point in baseline mortality coincident with the changes

Incorporating Test Data for Small UAS at the Conceptual Design Level

Increasing demand for improved capabilities of small unmanned aircraft systems (sUAS) has generated interest in improving the design techniques for these vehicles. sUAS have typically been designed using iterative methods with multiple prototypes, but advancements in aircraft design software will make it possible to generate conceptual designs of very small VTOL aircraft with reduced hardware prototyping. This paper describes a research effort to generate a conceptual design of an approximately 6-lb quadcopter using the NASA rotorcraft design software NDARC. Wind tunnel and hover test data are used to validate and refine the conceptual design results. The effects of parametric design variations on vehicle scale are shown. The design study described herein shows that the NDARC software, which was designed for full-scale rotorcraft, can be used to design and evaluate sUAS vehicles