A Light Introduction to PBL

Non peer reviewe

Coloniser discourses in Capital Television nightly news, Waitangi Day 1996 : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Philosophy in Development Studies at Massey University

Coloniser's discourses which attempted to justify and redeem many of the devastating processes of colonisation around the world have been (re)constructed and repeated in Aotearoa since the 1840's. They include notions of 'progress', 'civilisation', 'social evolution', and the categorisation of bodies into 'races' and 'genders'. These discourses have shaped many of the identities of people living in Aotearoa as well as the political, economic and social developmental path of this country. In 1996 I argue many of these coloniser discourses are repeated and reinforced through the television current affairs and news coverage of Waitangi Day 1996. This being so I argue that imagery is a vital area for academic study because it is through images that we present ourselves to ourselves. Following Clifford and Foucault I approach the 1996 Waitangi Day television news coverage as (re)presentations and constructions of 'truth'. I argue these 'truths' always involve a (re)production of certain political, economic and social discourses at the expense of others. I use theorists such as Irwin, Evans, Dyer and hooks to explore and explain the ways in which different discourses and experiences, some of which may be called anti-colonial, are marginalised by coloniser discourses and journalistic conventions. Using a post structuralist discourse analysis I identify how discourses of 'race' and 'gender' are deployed in Wellington's Capital Television nightly news coverage on 1996 Waitangi Day. In this programme, which claims to present an unmediated 'truth' surrounding the events of 1996 Waitangi Day, I argue that certain voices and experiences are given legitimacy while others are silenced and marginalised. I conclude that generally it is European/New Zealand and male voices which are heard at the expense of Māori and women. I argue that those who do wish to highlight the legacy of colonial ideas in the television media, through legitimate protest, for example Māori sovereignty groups and Pākehā supporters, are marginalised as 'protesters' and 'stirrers' disconnected from their communities and from 'real New Zealanders' on this particular day

The population of galaxy-galaxy strong lenses in forthcoming optical imaging surveys

Ongoing and future imaging surveys represent significant improvements in depth, area and seeing compared to current data-sets. These improvements offer the opportunity to discover up to three orders of magnitude more galaxy-galaxy strong lenses than are currently known. In this work we forecast the number of lenses discoverable in forthcoming surveys and simulate their properties. We generate a population of statistically realistic strong lenses and simulate observations of this population for the Dark Energy Survey (DES), Large Synoptic Survey Telescope (LSST) and Euclid surveys. We verify our model against the galaxy-scale lens search of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), predicting 250 discoverable lenses compared to 220 found by Gavazzi et al (2014). The predicted Einstein radius distribution is also remarkably similar to that found by Sonnenfeld et al (2013). For future surveys we find that, assuming Poisson limited lens galaxy subtraction, searches in DES, LSST and Euclid datasets should discover 2400, 120000, and 170000 galaxy-galaxy strong lenses respectively. Finders using blue minus red (g-i) difference imaging for lens subtraction can discover 1300 and 62000 lenses in DES and LSST. The uncertainties on the model are dominated by the high redshift source population which typically gives fractional errors on the discoverable lens number at the tens of percent level. We find that doubling the signal-to-noise ratio required for a lens to be detectable, approximately halves the number of detectable lenses in each survey, indicating the importance of understanding the selection function and sensitivity of future lens finders in interpreting strong lens statistics. We make our population forecasting and simulated observation codes publicly available so that the selection function of strong lens finders can easily be calibrated.Comment: Accepted for publication in ApJ. The code is publicly available at http://github.com/tcollett/LensPop . Tables of properties of the lenses discoverable by DES, LSST and Euclid are also available at the same ur

Wavefunction Collapse and Random Walk

Wavefunction collapse models modify Schrodinger's equation so that it describes the rapid evolution of a superposition of macroscopically distinguishable states to one of them. This provides a phenomenological basis for a physical resolution to the so-called "measurement problem." Such models have experimentally testable differences from standard quantum theory. The most well developed such model at present is the Continuous Spontaneous Localization (CSL) model in which a fluctuating classical field interacts with particles to cause collapse. One "side effect" of this interaction is that the field imparts momentum to particles, causing a small blob of matter to undergo random walk. Here we explore this in order to supply predictions which could be experimentally tested. We examine the translational diffusion of a sphere and a disc, and the rotational diffusion of a disc, according to CSL. For example, we find that a disc of radius 2 cdot 10^{-5} cm and thickness 0.5 cdot 10^{-5} cm diffuses through 2 pi rad in about 70sec (this assumes the "standard" CSL parameter values). The comparable rms diffusion of standard quantum theory is smaller than this by a factor 10^-3. At the reported pressure of < 5 cdot10^{-17} Torr, achieved at 4.2^{circ} K, the mean time between air molecule collisions with the disc is approximately 45min (and the diffusion caused by photon collisons is utterly negligible). This is ample time for observation of the putative CSL diffusion over a wide range of parameters. This encourages consideration of how such an experiment may actually be performed, and the paper closes with some thoughts on this subjectComment: 27 pages, 2 figure

Bi-directional route learning in wood ants

Some ants and bees readily learn visually guided routes between their nests and feeding sites. They can learn the appearance of visual landmarks for the food-bound or homeward segment of the route when these landmarks are only present during that particular segment of their round trip. We show here that wood ants can also acquire landmark information for guiding their homeward path while running their food-bound path, and that this information may be picked up, when ants briefly reverse direction and retrace their steps for a short distance. These short periods of looking back tend to occur early in route acquisition and are more frequent on homeward than on food-bound segments

Cosmological Constraints from the double source plane lens SDSSJ0946+1006

We present constraints on the equation of state of dark energy, $w$, and the total matter density, $\Omega_{\mathrm{M}}$, derived from the double-source-plane strong lens SDSSJ0946+1006, the first cosmological measurement with a galaxy-scale double-source-plane lens. By modelling the primary lens with an elliptical power-law mass distribution, and including perturbative lensing by the first source, we are able to constrain the cosmological scaling factor in this system to be $\beta^{-1}=1.404 \pm 0.016$, which implies $\Omega_{\mathrm{M}}= 0.33_{-0.26}^{+0.33}$ for a flat $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology. Combining with a cosmic microwave background prior from Planck, we find $w$ = $-1.17^{+0.20}_{-0.21}$ assuming a flat $w$CDM cosmology. This inference shifts the posterior by 1${\sigma}$ and improves the precision by 30 per cent with respect to Planck alone, and demonstrates the utility of combining simple, galaxy-scale multiple-source-plane lenses with other cosmological probes to improve precision and test for residual systematic biases.Comment: 9 Pages, 7 Figures. Updated version as published in MNRA