RATLER: Robotic All-Terrain Lunar Exploration Rover

A robotic rover vehicle designed for use in the exploration of the Lunar surface is described. The Robotic All-Terrain Lunar Exploration Rover (RATLER) is a four wheeled all-wheel-drive dual-body vehicle. A uniquely simple method of chassis articulation is employed which allows all four wheels to remain in contact with the ground, even while climbing over step-like obstacles as large as 1.3 wheel diameters. Skid steering and modular construction are used to produce a simple, rugged, highly agile mobility chassis with a reduction in the number of parts required when compared to current designs being considered for planetary exploration missions. The design configuration, mobility parameters, and performance of several existing RATLER prototypes are discussed

Large droplet impact on water layers

The impact of large droplets onto an otherwise undisturbed layer of water is considered. The work, which is motivated primarily with regard to aircraft icing, is to try and help understand the role of splashing on the formation of ice on a wing, in particular for large droplets where splash appears, to have a significant effect. Analytical and numerical approaches are used to investigate a single droplet impact onto a water layer. The flow for small times after impact is determined analytically, for both direct and oblique impacts. The impact is also examined numerically using the volume of fluid (VOF) method. At small times there are promising comparisons between the numerical results, the analytical solution and experimental work capturing the ejector sheet. At larger times there is qualitative agreement with experiments and related simulations. Various cases are considered, varying the droplet size to layer depth ratio, including surface roughness, droplet distortion and air effects. The amount of fluid splashed by such an impact is examined and is found to increase with droplet size and to be significantly influenced by surface roughness. The makeup of the splash is also considered, tracking the incoming fluid, and the splash is found to consist mostly of fluid originating in the layer

Estudo dos líquenes dos Açores. Parte 2 - Líquenes das encostas de altitude da montanha do Pico. Comparação entre as floras de líquenes de altitude das ilhas dos Açores, Madeira e Canárias

Descreve-se a flora de líquenes das encostas alas do Pico, a maior montanha dos Açores, entre 1200-2300 m de altitude. Reconhecem-se duas zonas florísticas distintas: uma elevada, 1500-2300 m, acima da camada de inversão, pobre em espécies, e uma zona baixa, entre 1200-1500 m com maior diversidade específica, dependente da persistência da faixa de nuvens. Registaram-se 49 espécies de líquenes, 14 das quais são novas ocorrências para os Açores, incluindo duas que se descrevem de novo: Ochrolechia azorica e Stereocaulon macaronesicum. Compara-se a comunidade de líquenes acima de faixa de nuvens do Pico, dominada principalmente por Stereocaulon e Placopsis gelida, com as floras documentadas de altitude de outras ilhas da Macaronésia. Considera-se que a escassez de espécies de líquenes nas encostas de altitude do Pico é, em primeiro lugar, o resultado do isolamento recente dos Açores, mas também da natureza recente do substracto e das severas condições climatéricas.ABSTRACT: The lichen flora of the upper slopes of Pico, the major mountain in the Azores, is described between altitudes 1200-2300 m. Two distinct floristic zones are recognised: an upper, species poor, zone from 1500-2300 m above the inversion layer and a lower, more species diverse, zone from 1200-1500 m dependent on the persistence of the cloud layer, 49 species are reported, 14 of which are new records for the Azores, including two which are newly described: Ochrolechia azorica and Stereocaulon macaronesicum. The lichen communities above the cloud layer, dominated principally by species of Stereocaulon and Placopsis gelida are compared with those of other documented floras of Macaronesian islands al high elevations. The paucity of species on the upper slopes of Pico is considered to be primarily the result of the isolation of the Azores, the recent nature of the substrate and severity of the climatic conditions

International Differences in Response to Common External Shocks: The Role of Purchasing Power Parity

Published in connection with a visit at the IIE

MODISTools - downloading and processing MODIS remotely sensed data in R

Remotely sensed data – available at medium to high resolution across global spatial and temporal scales – are a valuable resource for ecologists. In particular, products from NASA's MODerate-resolution Imaging Spectroradiometer (MODIS), providing twice-daily global coverage, have been widely used for ecological applications. We present MODISTools, an R package designed to improve the accessing, downloading, and processing of remotely sensed MODIS data. MODISTools automates the process of data downloading and processing from any number of locations, time periods, and MODIS products. This automation reduces the risk of human error, and the researcher effort required compared to manual per-location downloads. The package will be particularly useful for ecological studies that include multiple sites, such as meta-analyses, observation networks, and globally distributed experiments. We give examples of the simple, reproducible workflow that MODISTools provides and of the checks that are carried out in the process. The end product is in a format that is amenable to statistical modeling. We analyzed the relationship between species richness across multiple higher taxa observed at 526 sites in temperate forests and vegetation indices, measures of aboveground net primary productivity. We downloaded MODIS derived vegetation index time series for each location where the species richness had been sampled, and summarized the data into three measures: maximum time-series value, temporal mean, and temporal variability. On average, species richness covaried positively with our vegetation index measures. Different higher taxa show different positive relationships with vegetation indices. Models had high R2 values, suggesting higher taxon identity and a gradient of vegetation index together explain most of the variation in species richness in our data. MODISTools can be used on Windows, Mac, and Linux platforms, and is available from CRAN and GitHub (https://github.com/seantuck12/MODISTools)

Prepsolv (TM): The optimum alternative to 1,1,1-trichloroethane and methyl ethyl ketone for hand-wipe cleaning of aerospace materials

Engineers at Hercules Aerospace, a rocket motor manufacturer in Utah, have worked closely with chemists at Glidco Organics to study the feasibility of using terpenes for zero-residue wipe cleaning. The result of this work is a technological breakthrough, in which the barrier to ultra-low non-volatile residue formation has been broken. After 2 years of development and testing, SCM Glidco Organics has announced the availability of Glidsafe(registered trademark) Prepsolv(TM): a state-of-the-art ultra-low residue terpene wipe cleaning agent that does not require rinsing. Prepsolv(TM) can successfully be used in simple hand-wipe cleaning processes without fear of leaving surface residues. Industry testing has confirmed that Prepsolv(TM) is not only highly effective, but can even be less expensive to use than traditional cleaning solvents like methyl chloroform. This paper addresses the features and benefits of Prepsolv(TM), and presents performance and material compatibility data that characterizes this unique cleaning agent. Since its commercialization, Hercules Aerospace has chosen Prepsolv(TM) as the optimum cleaning agent to replace ozone-depleting solvents in their weapons factory in Magna, UT. Likewise, Boeing has approved Prepsolv(TM) for cleaning components in the manufacture of commercial aircraft at their facilities in Seattle, WA and Wichita, KS. Additional approvals are forthcoming for this uniquely safe and effective solvent

Local species assemblages are influenced more by past than current dissimilarities in photosynthetic activity

Most land on Earth has been changed by humans and past changes of land can have lasting influences on current species assemblages. Yet few globally representative studies explicitly consider such influences even though auxiliary data, such as from remote sensing, are readily available. Time series of satellite-derived data have been commonly used to quantify differences in land-surface attributes such as vegetation cover, which will among other things be influenced by anthropogenic land conversions and modifications. Here we quantify differences in current and past (up to five years before sampling) vegetation cover, and assess whether such differences differentially influence taxonomic and functional groups of species assemblages between spatial pairs of sites. Specifically, we correlated between-site dissimilarity in photosynthetic activity of vegetation (the Enhanced Vegetation Index) with the corresponding dissimilarity in local species assemblage composition from a global database using a common metric for both, the Bray-Curtis index. We found that dissimilarity in species assemblage composition was on average more influenced by dissimilarity in past than current photosynthetic activity, and that the influence of past dissimilarity increased when longer time periods were considered. Responses to past dissimilarity in photosynthetic activity also differed among taxonomic groups (plants, invertebrates, amphibians, reptiles, birds and mammals), with reptiles being among the most influenced by more dissimilar past photosynthetic activity. Furthermore, we found that assemblages dominated by smaller and more vegetation-dependent species tended to be more influenced by dissimilarity in past photosynthetic activity than prey-dependent species. Overall, our results have implications for studies that investigate species responses to current environmental changes and highlight the importance of past changes continuing to influence local species assemblage composition. We demonstrate how local species assemblages and satellite-derived data can be linked and provide suggestions for future studies on how to assess the influence of past environmental changes on biodiversity

Religious morality - work and wealth: The relevance of religiously based moral principles to commercial activities in Australia

The corporate collapses that have occurred in Australia and elsewhere in recent years are of major importance not only to investors and creditors, but to all of those who are interested in and concerned with the conduct of commercial activities. It was inevitable that attention would focus on causes, questions being asked as to the conduct and behaviour of those responsible for the control of the corporate activities. It is to the latter that the discussion yet to follow in this thesis is directed. It is maintained that if the relevant executives had been guided by and had applied ethical conduct religiously based, that is, religiously derived norms of behaviour, in their commercial decision-making process that the errors of judgement that led, at least in part, to the financial failures might not have occurred. The discussion raises issues of morality, of business morality, and the extent to which recognition of the relevance of the tenets of religious morality can play a part in influencing good corporate governance. The question is asked, can a company's Code of Conduct be structured in such a way that it provides assistance to the executive, management personnel and other employees on moral issues at a time when they are called upon to make difficult ethical decisions? Moral and ethical considerations can be identified, but unless the individual has confidence in their relevance to a particular situation, they may well be put aside or disregarded when a decision is being made. A process needs to be found for incorporating in them material which becomes part and parcel of a corporate ethos or mentality, something that is a point of reference for good governance. If there is to be an expressed morality which impinges on commercial behaviour, it should be a morality of belief and of persuasion. It should be sufficient to motivate an individual in the conduct of the affairs over which that person has control or influence, to pass it on and communicate it to others in a convincing way. For this is the lesson of history. The ideas of a vocation and the infinite worth of each and every person, have seeped into and been absorbed by 'Western' consciousness. The source of the beliefs, deeply held and demonstrated, is Judaism and Christianity. The thesis seeks to obtain insight into the concept of morality and ethical standards in order to ascertain how best they can be aligned with economic activity

Advanced power sources for space missions

Approaches to satisfying the power requirements of space-based Strategic Defense Initiative (SDI) missions are studied. The power requirements for non-SDI military space missions and for civil space missions of the National Aeronautics and Space Administration (NASA) are also considered. The more demanding SDI power requirements appear to encompass many, if not all, of the power requirements for those missions. Study results indicate that practical fulfillment of SDI requirements will necessitate substantial advances in the state of the art of power technology. SDI goals include the capability to operate space-based beam weapons, sometimes referred to as directed-energy weapons. Such weapons pose unprecedented power requirements, both during preparation for battle and during battle conditions. The power regimes for these two sets of applications are referred to as alert mode and burst mode, respectively. Alert-mode power requirements are presently stated to range from about 100 kW to a few megawatts for cumulative durations of about a year or more. Burst-mode power requirements are roughly estimated to range from tens to hundreds of megawatts for durations of a few hundred to a few thousand seconds. There are two likely energy sources, chemical and nuclear, for powering SDI directed-energy weapons during the alert and burst modes. The choice between chemical and nuclear space power systems depends in large part on the total duration during which power must be provided. Complete study findings, conclusions, and eight recommendations are reported