Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission

We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of λ3.6 cm. The moderate ring opening angle (B≈15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.     

An operational multiscale system for hazards prediction, mapping, and response

By definition, a crisis is a situation that requires assistance to be managed. Hence, response to a crisis involves the merging of local and non-local emergency response personnel. In this situation, it is critical that each participant: (1) know the roles and responsibilities of each of the other participants; (2) know the capabilities of each of the participants; and (3) have a common basis for action. For many types of natural disasters, this entails having a common operational picture of the unfolding events, including detailed information on the weather, both current and forecasted, that may impact on either the emergency itself or on response activities. The Consequences Assessment Tool Set (CATS) is a comprehensive package of hazard prediction models and casualty and damage assessment tools that provides a linkage between a modeled or observed effect and the attendant consequences for populations, infrastructure, and resources, and, hence, provides the common operational picture for emergency response. The Operational Multiscale Environment model with Grid Adaptivity (OMEGA) is an atmospheric simulation system that links the latest methods in computational fluid dynamics and high-resolution gridding technologies with numerical weather prediction to provide specific weather analysis and forecast capability that can be merged into the geographic information system framework of CATS. This paper documents the problem of emergency response as an end-to-end system and presents the integrated CATS–OMEGA system as a prototype of such a system that has been used successfully in a number of different situations.     

Optimization of an ocean thermal energy conversion system

The optimum performance of a simple Rankine cycle ocean thermal energy conversion plant is investigated analytically. It is shown that the ratio of maximum net power output to heat exchanger surface area varies as H(Δt − t₀)² where H describes the overall heat transfer properties of the evaporator and condenser, Δt is the temperature difference between the warm and cold sea water supplies, and t₀ is a parameter depending primarily upon the pressure drops across the warm and cold sea water pumping systems. The model is relatively insensitive to the choice of working fluid, although ammonia is used as the illustrative example.     

Racism and Intolerance in Eastern Australia: a geographic perspective

Racism has become a fact of life in Australia over the past decade or so, yet there are relatively few studies of its nature or extent, and still fewer on its geography. Using a social constructivist approach, this study draws on a survey of 5056 respondents to investigate attitudes to racism and cultural diversity in New South Wales and Queensland, and of perceptions of out-groups as instances of ‘strangers in our midst’. On racism, results show the presence of a continuum of attitudes ranging from generally tolerant to generally intolerant, a presence which cuts across compositional (social or aspatial) characteristics to emphasise the existence of a distinctive geography, an everywhere different nature to racist and non-racist attitudes which transcends urban–rural and traditional social layers. On the other hand, perceptions of out-groups are not uniformly correlated with presence or absence of cultural diversity. In many cases, the ability to make judgements about significant ‘others’ or out-groups has been shown to relate more to abstract notions of self and national identity, reproduced in public by mainstream news media and political leaders. In particular, it may reflect an Anglo (or Anglo-Celtic) view on nationalism, which is a hallmark of the ‘new racism’: an assimilationist or ethnocultural view of Australian society which is different from the ‘civic nation’ ideal envisaged by multiculturalism. That the geography of attitudes and perceptions people have towards and about different cultural groups is so ‘everywhere different’ has important implications for attempts to address and redress issues of intolerance in Australia.     

The International Laser Ranging Service and its support for IGGOS

The International Laser Ranging Service (ILRS) was established in September 1998 as a service within the IAG to support programs in geodetic, geophysical, and lunar research activities and to provide data products to the International Earth Rotation Service (IERS) in support of its prime objectives. Now in operation for 5 years, the ILRS develops: (1) the standards and specifications necessary for product consistency and (2) the priorities and tracking strategies required to maximize network efficiency. The service collects, merges, analyzes, archives and distributes satellite and lunar laser ranging data to satisfy a variety of scientific, engineering, and operational needs and encourages the application of new technologies to enhance the quality, quantity, and cost effectiveness of its data products. The ILRS works with: (1) the global network to improve station performance; (2) new satellite missions in the design and building of retroreflector targets to maximize data quality and quantity and (3) science programs to optimize scientific data yield. The ILRS Central Bureau maintains a comprehensive web site as the primary vehicle for the distribution of information within the ILRS community. The site, which can be accessed at: http://ilrs.gsfc.nasa.gov is also available at mirrored sites at the Communications Research Laboratory (CRL) in Tokyo and the European Data Center (EDC) in Munich.During the last 2 years, the ILRS has addressed very important challenges: (1) data from the field stations are now submitted hourly and made available immediately through the data centers for access by the user community; (2) tracking on low satellites has been significantly improved through the sub-daily issue of predictions, drag functions, and the real-time exchange of time biases; (3) analysis products are now submitted in SINEX format for compatibility with the other space geodesy techniques; (4) the Analysis Working Group is heavily engaged in Pilot Projects as it works toward an ILRS “standard” global solution and (5) SLR has significantly increased its participation in the International Terrestrial Reference Frame (ITRF) activity, which is important to the success of IGGOS.     

Petrology and petrogenesis of the Ministers Island dike,southwest New Brunswick,Canada

The Ministers Island dike in southwest New Brunswick is a quartz tholeiitic member of the Late Triassic to Early Jurassic dike suite that outcrops along the east coast of North America. The dike's phenocryst assemblage is orthopyroxene + augite + plagioclase. The combination of petrographic, chemical (both phase and whole rock), isotopic and experimental work on representative samples from the dike places important constraints on the petrogenesis of the Ministers Island dike and by analogy on the other members of the dike suite. The petrographic, analytical and experimental results show that the Ministers Island dike magma underwent high pressure (0.8 to 1.0 GPa) fractionation of augite, followed by augite + orthopyroxene, and finally augite + plagioclase. The absence of olivine as either a phenocryst or an experimentally observed high pressure liquidus phase indicates that the magma evolved away from the Ol-Cpx-Opx-Plag pseudo-invariant point while still at high pressure and there was sufficient time for any olivine to settle out of the magma prior to emplacement of the dike. The Sr and Nd isotopic results support a metasomatised mantle source similar to EMI but with slightly more radiogenic Nd.     

Rapid sampling of organic matter in flooded soils and sediments

Estuaries and Coasts - A coring system using a compressed air supply and a sediment shaking procedure using a soil dispersant are described which greatly simplify and shorten the task of...