New Media, First Time Voters and the 2007 Australian Federal Election

Researchers suggest that the youth of today has disengaged from the political landscape in Australia. However, the online realm provides potential first time voters an avenue in which to engage in politics in an environment that is generally associated with a youthful demographic. New media tactics utilised during the 2007 Australian federal election aimed to not only attract youthful voters, but also to educate and deliver policy on a level generally associated with the 18-24 demographic. This study explored the effectiveness of new media in the political communication context, in particular with relation to first time voters. This research found that first time voters were not as engaged as predicted, and that the third party sites were more popular with undecided voters than the formal political party sites in voter influence

New nuclear three-body clusters \phi{NN}

Binding energies of three-body systems of the type \phi+2N are estimated. Due to the strong attraction between \phi-meson and nucleon, suggested in different approaches, bound states can appear in systems like \phi+np (singlet and triplet) and \phi+pp. This indicates the principal possibility of the formation of new nuclear clusters

Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with M~0.9 M_sun

Type Ia supernovae (SNe Ia) are thought to result from thermonuclear explosions of carbon-oxygen white dwarf stars. Existing models generally explain the observed properties, with the exception of the sub-luminous 1991-bg-like supernovae. It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but hitherto simulations have failed to produce an explosion. Here we report a simulation of the merger of two equal-mass white dwarfs that leads to an underluminous explosion, though at the expense of requiring a single common-envelope phase, and component masses of ~0.9 M_sun. The light curve is too broad, but the synthesized spectra, red colour and low expansion velocities are all close to what is observed for sub-luminous 1991bg-like events. While mass ratios can be slightly less than one and still produce an underluminous event, the masses have to be in the range 0.83-0.9 M_sun.Comment: Accepted to Natur

Granular Impact: A Grain-scale Approach

This work summarizes a series of studies on two-dimensional granular impact, where an intruding object strikes a granular material at high speed. Many previous studies on granular impact have used a macroscopic force law, which is dominated by an inertial drag term proportional to the intruder velocity squared. The primary focus here is on the microscopic force response of the granular material, and how the grain-scale effects give rise to this inertial drag term. We show that the inertial drag arises from intermittent collisions with force-chain-like structures. We construct a simple collisional model to explain the inertial drag, as well as off-axis instability and rotations. Finally, we show how the granular response changes when the intruder speed approaches $d/t_c$, leading to a failure of the inertial drag description in this regime. Here, $d$ is the mean particle diameter and $t_c$ the characteristic momentum-transfer time between two grains.Comment: This is draft version of a book chapter appearing in "Rapid Penetration into Granular Media" (eds. Iskander et al.

Diversity of supernovae Ia determined using equivalent widths of Si II 4000

Spectroscopic and photometric properties of low and high-z supernovae Ia (SNe Ia) have been analyzed in order to achieve a better understanding of their diversity and to identify possible SN Ia sub-types. We use wavelet transformed spectra in which one can easily measure spectral features. We investigate the \ion{Si}{II} 4000 equivalent width (EW_w\lbrace\ion{Si}{II}\rbrace). The ability and, especially, the ease in extending the method to SNe at high-$z$ is demonstrated. We applied the method to 110 SNe Ia and found correlations between EW_w\lbrace\ion{Si}{II}\rbrace and parameters related to the light-curve shape for 88 supernovae with available photometry. No evidence for evolution of EW_w\lbrace\ion{Si}{II}\rbrace with redshift is seen. Three sub-classes of SNe Ia were confirmed using an independent cluster analysis with only light-curve shape, colour, and EW_w\lbrace\ion{Si}{II}\rbrace. SNe from high-$z$ samples seem to follow a similar grouping to nearby objects. The EW_w\lbrace\ion{Si}{II}\rbrace value measured on a single spectrum may point towards SN Ia sub-classification, avoiding the need for expansion velocity gradient calculations.Comment: 12 pages, 5 figure

A constitutive law for dense granular flows

A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.Comment: http://www.nature.com/nature/journal/v441/n7094/abs/nature04801.htm

MRI investigation of granular interface rheology using a new cylinder shear apparatus

The rheology of granular materials near an interface is investigated through proton magnetic resonance imaging. A new cylinder shear apparatus has been inserted in the MRI device, which allows the control of the radial confining pressure exerted by the outer wall on the grains and the measurement of the torque on the inner shearing cylinder. A multi-layer velocimetry sequence has been developed for the simultaneous measurement of velocity profiles in different sample zones, while the measurement of the solid fraction profile is based on static imaging of the sample. This study describes the influence of the roughness of the shearing interface and of the transverse confining walls on the granular interface rheology

Type Ia Supernovae as Stellar Endpoints and Cosmological Tools

Empirically, Type Ia supernovae are the most useful, precise, and mature tools for determining astronomical distances. Acting as calibrated candles they revealed the presence of dark energy and are being used to measure its properties. However, the nature of the SN Ia explosion, and the progenitors involved, have remained elusive, even after seven decades of research. But now new large surveys are bringing about a paradigm shift --- we can finally compare samples of hundreds of supernovae to isolate critical variables. As a result of this, and advances in modeling, breakthroughs in understanding all aspects of SNe Ia are finally starting to happen.Comment: Invited review for Nature Communications. Final published version. Shortened, update

Synthesis and biochemical studies of 17-substituted androst-3-enes and 3,4-epoxyandrostanes as aromatase inhibitors

http://www.sciencedirect.com/science/article/B6TC9-4T0WJXG-2/2/58305e64e3c068f352293a693f168db

The correlation between C/O ratio, metallicity and the initial WD mass for SNe Ia

In this paper, we want to check whether or not the carbon abundance can be affected by initial metallicity. We calculated a series of stellar evolution. We found that when $Z\leq0.02$, the carbon abundance is almost independent of metallicity if it is plotted against the initial WD mass. However, when $Z>0.02$, the carbon abundance is not only a function of the initial WD mass, but also metallicity, i.e. for a given initial WD mass, the higher the metallicity, the lower the carbon abundance. Based on some previous studies, i.e. both a high metallicity and a low carbon abundance lead to a lower production of $^{\rm 56}$Ni formed during SN Ia explosion, the effects of the carbon abundance and the metallicity on the amount of $^{\rm 56}$Ni are enhanced by each other, which may account for the variation of maximum luminosity of SNe Ia, at least qualitatively. Considering that the central density of WD before supernova explosion may also play a role on the production of $^{\rm 56}$Ni and the carbon abundance, the metallicity and the central density are all determined by the initial parameters of progenitor system, i.e. the initial WD mass, metallicity, orbital period and secondary mass, the amount of $^{\rm 56}$Ni might be a function of the initial parameters. Then, our results might construct a bridge linking the progenitor model and the explosion model of SNe Ia.Comment: 7pages, 4 figures, accepted for publication in A&