Australian National University

About: Australian National University is a education organization based out in Canberra, Australian Capital Territory, Australia. It is known for research contribution in the topics: Population & Galaxy. The organization has 34419 authors who have published 109261 publications receiving 4315448 citations. The organization is also known as: The Australian National University & ANU.

Experimental deformation of partially-melted granite

Abstract: An account is given of the experimental deformation of partially-melted granite with melt fractions up to 25% at 800 °C and 300 MPa confining pressure in constant strainrate tests between 10−3 and 10−6 S−1, creep tests and cycling tests Microscopic study reveals that under these conditions most of the uniform deformation prior to macroscopic shear failure is accomplished by melt redistribution into films perpendicular to the least compressive stress, and by axial fracturing of grains, the latter occurring even at low macroscopic differential stress The strenght of the partially-melted rock at 10−5 S−1 is found to decrease gradually from about 250 MPa at 5 vol% melt to about 60 MPa at 15 % melt, and then to drop rapidly to less than 1 MPa at 24% melt The critical melt fraction separating granular-framework-controlled flow behaviour from suspension-like behaviour is deduced to be approximately 30 to 35 vol% At low melt fractions the deforming rock tends to take up externally available melt by a mechanism of dilatancy pumping The relevance of these results to natural conditions involving partially-melted rocks is discussed

Should agricultural policies encourage land sparing or wildlife‐friendly farming?

Abstract: As the demands on agricultural lands to produce food, fuel, and fiber continue to expand, effective strategies are urgently needed to balance biodiversity conservation and agricultural production. “Land sparing” and “wildlife-friendly farming” have been proposed as seemingly opposing strategies to achieve this balance. In land sparing, homogeneous areas of farmland are managed to maximize yields, while separate reserves target biodiversity conservation. Wildlife-friendly farming, in contrast, integrates conservation and production within more heterogeneous landscapes. Different scientific traditions underpin the two approaches. Land sparing is associated with an island model of modified landscapes, where islands of nature are seen as separate from human activities. This simple dichotomy makes land sparing easily compatible with optimization methods that attempt to allocate land uses in the most efficient way. In contrast, wildlife-friendly farming emphasizes heterogeneity, resilience, and ecological inter...

Quantum spin Hall effect of light

Abstract: Maxwell’s equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are evanescent waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in evanescent waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell’s theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.

Does old age reduce the risk of anxiety and depression? A review of epidemiological studies across the adult life span.

Abstract: Background. There is considerable disagreement about what happens to the risk of anxiety and depression disorders and symptoms as people get older.Methods. A search was made for studies that examine the occurrence of anxiety, depression or general distress across the adult life span. To be included, a study had to involve a general population sample ranging in age from at least the 30s to 65 and over and use the same assessment method at each age.Results. There was no consistent pattern across studies for age differences in the occurrence of anxiety, depression or distress. The most common trend found was for an initial rise across age groups, followed by a drop. Two major factors producing this variability in results were age biases in assessment of anxiety and depression and the masking effect of other risk factors that vary with age. When other risk factors were statistically controlled, a more consistent pattern emerged, with most studies finding a decrease in anxiety, depression and distress across age groups. This decrease cannot be accounted for by exclusion of elderly people in institutional care from epidemiological surveys or by selective mortality of people with anxiety or depression.Conclusion. There is some evidence that ageing is associated with an intrinsic reduction in susceptibility to anxiety and depression. However, longitudinal studies covering the adult life span are needed to distinguish ageing from cohort effects. More attention needs to be given to understanding the mechanism behind any ageing-related reduction in risk for anxiety and depression with age. Possible factors are decreased emotional responsiveness with age, increased emotional control and psychological immunization to stressful experiences.

Persistent growth of CO2 emissions and implications for reaching climate targets

Abstract: Efforts to limit climate change below a given temperature level require that global emissions of CO2 cumulated over time remain below a limited quota. This quota varies depending on the temperature level, the desired probability of staying below this level and the contributions of other gases. In spite of this restriction, global emissions of CO2 from fossil fuel combustion and cement production have continued to grow by 2.5% per year on average over the past decade. Two thirds of the CO2 emission quota consistent with a 2 °C temperature limit has already been used, and the total quota will likely be exhausted in a further 30 years at the 2014 emissions rates. We show that CO2 emissions track the high end of the latest generation of emissions scenarios, due to lower than anticipated carbon intensity improvements of emerging economies and higher global gross domestic product growth. In the absence of more stringent mitigation, these trends are set to continue and further reduce the remaining quota until the onset of a potential new climate agreement in 2020. Breaking current emission trends in the short term is key to retaining credible climate targets within a rapidly diminishing emission quota.