Macquarie University

About: Macquarie University is a education organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Population & Laser. The organization has 14075 authors who have published 47673 publications receiving 1416184 citations. The organization is also known as: Macquarie uni.

The RAVE survey: constraining the local Galactic escape speed

Abstract: We report new constraints on the local escape speed of our Galaxy. Our analysis is based on a sample of high-velocity stars from the RAVE survey and two previously published data sets. We use cosmological simulations of disc galaxy formation to motivate our assumptions on the shape of the velocity distribution, allowing for a significantly more precise measurement of the escape velocity compared to previous studies. We find that the escape velocity lies within the range 498

Comparative evolutionary ecology of seed size

Abstract: A seedling's chances of establishing successfully are likely to be affected by the quantity of metabolic reserves in the seed. Seed size is thought to evolve as a compromise between producing numerous smaller seeds, each with few resources, and fewer larger seeds, each with more resources. Seed size varies 10 11 -fold across plant species, so the compromise has been struck at very different levels. These basic ideas have been accepted for 50 years, and many studies have interpreted seed size differences between species by reference to larger seed size being adaptive under a variety of hazards. However, experimental tests of the benefits of large seed size in relation to particular hazards have been rare. More experiments are now being reported, but a consistent picture has yet to emerge. There is typically at least a 10 5 -fold range of seed mass between species even within a single area, suggesting that much seed size variation is evolutionarily associated with other plant attributes.

An introduction to long-memory time series models and fractional differencing

Abstract: The idea of fractional differencing is introduced in terms of the infinite filter that corresponds to the expansion of (1 - B)d. When the filter is applied to white noise, a class of time series is generated with distinctive properties, particularly in the very low frequencies and provides potentially useful long-memory forecasting properties. Such models are shown possibly to arise from aggregation of independent components. Generation and estimation of these models are considered and applications on generated and real data presented.