Orbitally induced oscillations in the East Antarctic ice sheet at the Oligocene/Miocene boundary

Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3-4 degreesC warmer than at present and atmospheric CO2 concentrations were twice as high as today(1), the Antarctic ice sheets may have been unstable(2-7). Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles(8-10). But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets(11). Here we present sediment data from shallow marine cores in the western Ross Sea that exhibit well dated cyclic variations, and which link the extent of the East Antarctic ice sheet directly to orbital cycles during the Oligocene/Miocene transition (24.1-23.7 Myr ago). Three rapidly deposited glaci-marine sequences are constrained to a period of less than 450 kyr by our age model, suggesting that orbital influences at the frequencies of obliquity (40 kyr) and eccentricity (125 kyr) controlled the oscillations of the ice margin at that time. An erosional hiatus covering 250 kyr provides direct evidence for a major episode of global cooling and ice-sheet expansion about 23.7 Myr ago, which had previously been inferred from oxygen isotope data (Mil event(5)).

Critical review of acid in situ leach uranium mining: 2. Soviet Block and Asia

The technique of in situ leach (ISL) uranium mining is well established in the USA, as well as being used extensively in Eastern Europe and the former Soviet Union. The method is being proposed and tested on uranium deposits in Australia, with sulphuric acid chemistry and no restoration of groundwater following mining. ISL mines in the former Soviet Union generally used acid reagents and were operated without due consideration given to environmental protection. At many former mine sites, the extent of groundwater contamination is significant because of high salinity, heavy metal and radionuclide concentrations compared with pre-mining and changes in the hydrogeological regime caused by mining. After the political collapse of the Soviet Union by the early 1990s, most uranium mines were shut down or ordered to be phased out by government policy. Programmes of restoration are now being undertaken but are proving technically difficult and hampered by a lack of adequate financial resources. The history and problems of acid ISL sites in countries of the former Soviet Union and Asia are presented in this study.

Peacebuilding in East Timor

This essay analyses some of the political, economic and social challenges of East Timer's transition to independence. It scrutinizes the ethical dimensions of building peace in a territory devastated by the combined effect of Indonesia's colonial occupation and the violent militia attacks of September 1999. The most difficult task ahead does not lie in the physical rebuilding of the territory-gargantuan as it may be-but in the more intricate and long-term rehabilitation of a traumatized society. The latter involves competing Timorese factions as well as a range of international actors, including the United Nations Transitional Authority, foreign governments, business institutions and various multilateral and bilateral donors. each having their own organizational leitmotifs and policy priorities. If not managed carefully, the reconstruction process could further exacerbate existing societal tensions and complicate the starch for peace and reconciliation. The essay identifies a number of crucial components necessary to counter such risks, including the need to promote popular participation in the rebuilding process. Without the legitimacy created by strong community involvement and grassroots participation in decision making, the task of national reconstruction may well become overwhelmed by conflict.

Asia Pacific security outlook 2000

Reviews the book 'Asia Pacific Security Outlook 2000,' edited by Richard W. Baker and Charles M. Morrison.

China and Southeast Asia

In the new millennium, no issue in international relations will be more important than how to accommodate the rising power of China. Many analysts, especially in the United States, see China as a significant threat to American interests in Asia. Washington has treaty commitments in both Northeast and Southeast Asia and retains a substantial military presence in the region. Beijing claims it does not seek to replace the United States reigning global hegemony, but seeks to promote a multi-polar world in which six states (the US, China, the EU, Russia, Japan, and India) would have pre-eminent status.

Reproduction in the squirrel glider, Petaurus norfolcensis (Petauridae) in south-east Queensland

Reproduction was studied across a three-year period in two south-east Queensland populations of the squirrel glider, Petaurus norfolcensis, by measuring morphological (body weight, scrotal diameter, cutaneous scent-gland activity, condition index) and physiological (plasma steroid levels) variables. Reproduction showed a seasonal pattern, with peak numbers of pouch young recorded in late autumn and winter. Declines in oestrogen concentrations outside the breeding period indicate that females are anoestrous in the summer months. Most (83%) reproductive females captured during the study were 2-3 years old, but all individuals over one year of age were found to have bred. Average litter size was 1.73 +/- 0.01 (n = 23). Scrotal diameter and testosterone concentrations showed no significant seasonal variation. It is suggested that this is due to the presence of both socially dominant and subordinate males in the data set. Maximum testosterone concentrations did coincide with periods of mating. The condition index showed no relationship with reproductive variables, but it is likely that this results from the manner in which the index was generated.

Field test of a model of migration of moths (Lepidoptera : Noctuidae) in inland Australia

A migration of Helicoverpa punctigera (Wallengren), Heliothis punctifera (Walker) and Agrotis munda Walker was tracked from Cameron Corner (29degrees00'S, 141degrees00'E) in inland Australia to the Wilcannia region, approximately 400 km to the south-east. A relatively isolated source population was located using a distribution model to predict winter breeding, and confirmed by surveys using sweep netting for larvae. When a synoptic weather pattern likely to produce suitable conditions for migration developed, moths were trapped in the source region. The next morning a simulation model of migration using wind-field data generated by a numerical weather-prediction model was run. Surveys using sweep netting for larvae, trapping and flush counts were then conducted in and around the predicted moth fallout area, approximately 400 km to the south-east. Pollen carried on the probosces of moths caught in this area was compared with that on moths caught in the source area. The survey data and pollen comparisons provided evidence that migration had occurred, and that the migration model gave accurate estimation of the fallout region. The ecological and economic implications of such migrations are discussed.

Comparative phylogeography of three rainforest-restricted lizards from mid-east Queensland

Several small isolates of rainforest situated on the central eastern coast of Australia are home to a rich herpetofauna, including four endemic species of leaftail geckos (Phyllurus spp.) and two skinks (Eulamprus spp.). To examine the extent and geographic pattern of historical subdivision among isolates, we assayed mtDNA variation in two species endemic to rainforests of this region (Phyllurus ossa and Eulamprus amplus) and, for comparison, a more widespread and less specialised lizard, Carlia rhomboidalis. There is a clear genetic signature of historical changes in population size and distribution in P. ossa that is consistent with Pleistocene (or earlier) rainforest contraction and subsequent expansion. Although more pronounced in the gecko, phylogeographic structure was congruent between E. amplus and P. ossa. In contrast to the saxicolous, rainforest-restricted P. ossa and E. amplus, the rainforest-generalist species, C. rhomboidalis, does not display strong geographic population structure. The differences in genetic population structure exhibited by the three species are consistent with species-specific differences in ecology.