Thermoremanent magnetization (TRM) of lunar samples

The TRM of the lunar breccia 10048-55 and the crystalline rocks 12053-47 and 14053-48 have been investigated. TRM is acquired linearly by 12053-47 and 10048-55 in fields of 100 to 1 oe. In contrast, the TRM of 14053-48 departs from linearity in the same range of fields. The AF stability of TRM acquired by the samples varies markedly. 10048-55 and 12053-47 are of intermediate hardness, such as would be expected for a TRM carried at least in part by fine grain particles of iron having high coercivity. 14053-48 has extremely soft TRM which is most probably carried predominantly by multidomain iron. Thermal demagnetization of the TRM of 10048-55 revealed well distributed blocking temperatures, but the TRM of 14053-48 has markedly bimodal blocking temperatures. Comparison of the characteristics of the NRM and the TRM of the three samples suggest that only the NRM of 14053-48 is likely to be primarily thermal in origin.     

The Geography of Racisms in NSW: A theoretical exploration and some preliminary findings from the mid-1990s

The spatial variation of racisms is an under-researched field of inquiry, certainly in Australia. This paper explores the geographies of racism in New South Wales. Responses to three opinion polls conducted between 1994 and 1996 were used to construct patterns of racisms across NSW. Preliminary findings suggest a substantive degree of racism in NSW. There was little evidence of an urban-rural variation in terms of ethnocentrism. Examination of regional variations confounds this simple division. Social Constructionist theory is put forward as a spatially sensitive theory for understanding and responding to the geographies of racism. The identification of regional variations in racism is crucial to the development of regionally specific anti-racism campaigns. This paper highlights the need for more comprehensive analyses of the varying causes and remedies for racisms.     

Resident action groups in Sydney: people power or rat‐bags?

This paper presents an analysis of a neglected area of study by geographers; that of resident action groups. During the 1980s there has been a significant increase in the number of resident action groups throughout Sydney. Resident activism has influenced local planning processes, the location of noxious facilities and subsequent urban form. This has initiated important reactions by government at both the local and State levels. Urban collective activisms have been hypothesised as single‐issue, self‐serving nimby groups. However, RAGs are also empowering forces, in which women and men are introduced to the political structures and become engaged in protest and resistance that can challenge the social and spatial order. RAGs can, either singularly or cumulatively, force a re‐aligning of existing power relations, and they can necessitate changed modes of governance (or govern‐mentality).     

Tree-top sampling from a helicopter - a new approach to gold exploration

Foliage from Douglas-fir (Pseudotsuga menziesii) tops was collected from 94 sites around the poorly exposed QR Au deposit in central British Columbia. Locally high concentrations of gold in ashed stems suggest a northwestward (down-ice) dispersion train of Au extending uphill for at least 500 m from the deposit. In addition, a down-slope, hydromorphic dispersion train is evident. All trees sampled are extremely rich in As, but the patterns of As distribution are less clearly related to the mineralization than those of Au enrichment. Summary statistics of analytical data for 35 elements are provided to serve as baseline information for any future studies.The sampling method, which is described in detail, is simple and cost-effective. In one hour the foliage of tree tops from about 50 sites, spaced at intervals of 200 m or more, can be collected by a three-person helicopter crew. The technique is particularly appropriate for rapidly screening rugged or heavily forested terrain, regardless of snow-cover, in order to establish priorities for ground follow-up exploration targets.     

Intensity determination by continuous thermal cycling

The advent of cryogenic magnetometers with which remanence can be measured at high sensitivity statically permits continuous thermal demagnetization and, in principle, a continuous version of the classic stepwise method of intensity determination. In the technique we have initially tried a field is trapped in the superconducting shield of the magnetometer throughout the experiment. The sample is then thermally cycled over progressively higher temperature ranges so that the incremental acquisition of partial thermoremanence (PTRM) and loss of the natural remanence (NRM) of the sample can be compared. In control experiments we have found that bad intensity estimates arise because the presence of the field causes difficulty in reliable separation of remanent and induced moments. A better approach is to heat and cool the sample in the required fields outside of the magnetometer and to insert it into the magnetometer only for the measurement of remanence. In this way it will be possible to cycle the sample to progressively higher temperatures and measure at elevated temperatures without cooling to room temperature, but one will measure remanence directly in zero field.     

Die Ladungsbilanz für eine verfeinerte Kristallstruktur von Stranskiit,Zn2 Cu(AsO4)2

Zusammenfassung Die Kristallstruktur des Stranskiits wurde mit neuen Meßdaten, die an einer aus Tsumeb stammenden Probe gewonnen worden waren, bis zuR=0,034 für 1239 unabhängige beobachtete Reflexe verfeinert. Von der verfeinerten Struktur wurde die Ladungsbilanz aufgestellt und besonders im Hinblick auf die Ladungsdeformation des Cu²⁺ diskutiert. Eine Mikrosondenanalyse derselben Probe ergab, daß die tatsächliche Zusammensetzung der angegebenen Formel entspricht.

---

Charge balance of a refined crystal structure of stranskiite, Zn₂Cu (AsO₄)₂

Summary The crystal structure of stranskiite was refined with new intensity data obtained from a specimen from Tsumeb toR=0.034 for 1234 observed independent reflections. The charge balance was calculated and discussed particularly with respect of the charge deformation of Cu²⁺. An electron probe microanalysis gave the result that the actual composition of the specimen corresponds to the given formula.

     

Examining the wake structure in Saturn's rings from microwave observations over varying ring opening angles and wavelengths

Over the last 15 to 20 years several high quality, high resolution data have been taken with the very large array (VLA). These data exhibit a wide range of ring opening angles (|B|=0 to 26°) and wavelengths (λ=0.7 to 20 cm). At these wavelengths the primary flux from the rings is scattered saturnian thermal emission, with a small contribution coming from the ring particles' own thermal emission. Much of the data do show signs of asymmetries due to wakes either on the ansae or the portion of the rings which occult the planet. As in previous work, we use our Monte Carlo radiative transfer code including idealized wakes [Dunn, D.E., Molnar, L.A., Fix, J.D., 2002. Icarus 160, 132-160; Dunn, D.E., Molnar, L.A., Niehof, J.T., de Pater, I., Lissauer, J.L., 2004. Icarus 171, 183-198] to model the relative contributions of the scattered and thermal radiation emanating from the rings and compare the results to that seen in the data. Although the models do give satisfactory fits to all of our data, we find that no single model can simulate the data at all different |B| and λ. We find that one model works best for moderate and low |B| and another one at higher |B|. The main difference between these models is the ratio of the wake width to their separation. We similarly find that the 2 cm data require higher density wakes than the longer wavelength data, perhaps caused by a preponderance of somewhat smaller ring material in the wakes. We further find evidence for an increase in the physical temperature of the rings with increasing |B|. Continuous observations are required to determine whether the above results regarding variations in wake parameters with |B| and λ are indeed caused by these parameters, or instead by changes over time.