1,029 research outputs found
Materialising energy and water resources in everyday practices: Insights for securing supply systems
Policies to secure energy and water supplies from the impacts of climate change are currently being developed or are in place in many developed nations. Little is known about how these policies of security, and the systems of resource provision they prioritise, affect householders' capacity to adapt to climate change. To better understand the connections between resource provision and consumption, this paper explores the notion that different 'energies' and 'waters' can be conceptualised as material elements of social practices, which shape the way practices are performed. We draw on a study of Australian migrants and their experiences with different resource provision systems in multiple countries, time periods and contexts across three generations. We discuss the differing characteristics of energy and water provision across three broad resource 'eras', and the way resources enable or reduce resourcefulness, adaptive capacity and resilience. We find that policy makers may inadvertently reduce householders' capacity to respond and adapt to climate change impacts by prioritising the resource characteristics of immateriality, abundance and homogeneity. We conclude that policy which prioritises the resource characteristics of materiality, diversity and scarcity is an important, underutilised and currently unacknowledged source of adaptive capacity
Damped Ly{\alpha} Absorption Systems in Semi-Analytic Models with Multiphase Gas
We investigate the properties of damped Ly{\alpha} absorption systems (DLAs)
in semi-analytic models of galaxy formation, including partitioning of cold gas
in galactic discs into atomic, molecular, and ionized phases with a molecular
gas-based star formation recipe. We investigate two approaches for partitioning
gas into these constituents: a pressure-based and a metallicity-based recipe.
We identify DLAs by passing lines of sight through our simulations to compute
HI column densities. We find that models with "standard" gas radial profiles -
where the average specific angular momentum of the gas disc is equal to that of
the host dark matter halo - fail to reproduce the observed column density
distribution of DLAs. These models also fail to reproduce the distribution of
velocity widths {\Delta}v, overproducing low {\Delta}v relative to high
{\Delta}v systems. Models with "extended" radial gas profiles - corresponding
to gas discs with higher specific angular momentum - are able to reproduce
quite well the column density distribution of absorbers over the column density
range 19 < log NHI < 22.5 in the redshift range 2 < z < 3.5. The model with
pressure-based gas partitioning also reproduces the observed line density of
DLAs, HI gas density, and {\Delta}v distribution at z < 3 remarkably well.
However all of the models investigated here underproduce DLAs and the HI gas
density at z > 3. If this is the case, the flatness in the number of DLAs and
HI gas density over the redshift interval 0 < z < 5 may be due to a cosmic
coincidence where the majority of DLAs at z > 3 arise from intergalactic gas in
filaments while those at z < 3 arise predominantly in galactic discs. We
further investigate the dependence of DLA metallicity on redshift and
{\Delta}v, and find reasonably good agreement with the observations,
particularly when including the effects of metallicity gradients (abbrv.).Comment: 27 pages, 15 figures, submitted to MNRA
The great Australian nightmare? The problem of escalating housing aspirations and expectations and adaptation to climate change
The dominant trend in Australian cities towards large, detached, energy intensive dwellings in poorly serviced, low-density, urban fringe locations, leaves governments, households and communities more vulnerable to the impacts of climate change and does little to aid mitigation. Given the multiple and competing objectives of the stakeholders involved, reducing domestic energy consumption is more complex than attempting to change what Shove (2010) refers to as the ABC ('attitudes, behaviours and choices') of individual householders. What is needed is a better understanding of the dynamic and integrated processes resulting in escalating expectations and aspirations for Australian housing. Along this vein, we suggest the 'great Australian dream' is actually becoming a great Australian nightmare. In our critique we investigate what is meant by a 'normal' home and how aspirations and expectations for housing have changed over time. Drawing on theories of social practice we look at what goes on inside homes to explore how everyday practices and the design of houses are mutually constitutive. In our analysis we find that seemingly common-place aspirations for housing are the result of changing practices, such as cooking, eating and entertaining, which are resulting in escalating trajectories of consumption. We conclude by suggesting how policy attention could be refocused on transforming the relationship between house design and everyday practice to address climate change
The Galaxy Angular Correlation Functions and Power Spectrum from the Two Micron All Sky Survey
We calculate the angular correlation function of galaxies in the Two Micron
All Sky Survey. We minimize the possible contamination by stars, dust, seeing
and sky brightness by studying their cross correlation with galaxy density, and
limiting the galaxy sample accordingly. We measure the correlation function at
scales between 1-18 arcdegs using a half million galaxies. We find a best fit
power law to the correlation function has a slope of 0.76 and an amplitude of
0.11. However, there are statistically significant oscillations around this
power law. The largest oscillation occurs at about 0.8 degrees, corresponding
to 2.8 h^{-1} Mpc at the median redshift of our survey, as expected in halo
occupation distribution descriptions of galaxy clustering.
We invert the angular correlation function using Singular Value Decomposition
to measure the three-dimensional power spectrum and find that it too is in good
agreement with previous measurements. A dip seen in the power spectrum at small
wavenumber k is statistically consistent with CDM-type power spectra. A fit of
CDM-type power spectra to k < 0.2 h Mpc^{-1} give constraints of
\Gamma_{eff}=0.116 and \sigma_8=0.96. This suggest a K_s-band linear bias of
1.1+/-0.2. This \Gamma_{eff} is different from the WMAP CMB derived value. On
small scales the power-law shape of our power spectrum is shallower than that
derived for the SDSS. These facts together imply a biasing of these different
galaxies that might be nonlinear, that might be either waveband or luminosity
dependent, and that might have a nonlocal origin.Comment: 14 pages, 20 figures, to be published in ApJ January 20th, revision
included two new figures, version with high resolution figures can be found
here http::ww
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Adapting the Assessing British Sign Language Development: Receptive Skills Test into American sign language
Signed languages continue to be a key element of deaf education programs that incorporate a bilingual approach to teaching and learning. In order to monitor the success of bilingual deaf education programs, and in particular to monitor the progress of children acquiring signed language, it is essential to develop an assessment tool of signed language skills. Although researchers have developed some checklists and experimental tests related to American Sign Language (ASL) assessment, at this time a standardized measure of ASL does not exist. There have been tests developed in other signed languages, for example, British Sign Language, that can serve as models in this area. The purpose of this study was to adapt the Assessing British Sign Language Development: Receptive Skills Test for use in ASL in order to begin the process of developing a standardized measure of ASL skills. The results suggest that collaboration between researchers in different signed languages can provide a valuable contribution toward filling the gap in the area of signed language assessment
The first detection of Far-Infrared emission associated with an extended HI disk. The case of NGC 891
Spiral galaxies in the Local Universe are commonly observed to be embedded in
extended disks of neutral hydrogen - the so called ``extended HI disks''. Based
on observations made using the ISOPHOT instrument on board the Infrared Space
Observatory, we report the first detection of cold dust in the extended HI disk
of a spiral galaxy. The detection was achieved through a dedicated deep
Far-Infrared observation of a large field encompassing the entire HI disk of
the edge-on spiral galaxy NGC 891. Our discovery indicates that the extended HI
disk of NGC 891 is not primordial in origin.Comment: accepted for publication in Astronomy and Astrophysics Letter
The SWELLS Survey. I. A large spectroscopically selected sample of edge-on late-type lens galaxies
The relative contribution of baryons and dark matter to the inner regions of
spiral galaxies provides critical clues to their formation and evolution, but
it is generally difficult to determine. For spiral galaxies that are strong
gravitational lenses, however, the combination of lensing and kinematic
observations can be used to break the disk-halo degeneracy. In turn, such data
constrain fundamental parameters such as i) the mass density profile slope and
axis ratio of the dark matter halo, and by comparison with dark matter-only
numerical simulations the modifications imposed by baryons; ii) the mass in
stars and therefore the overall star formation efficiency, and the amount of
feedback; iii) by comparison with stellar population synthesis models, the
normalization of the stellar initial mass function. In this first paper of a
series, we present a sample of 16 secure, 1 probable, and 6 possible strong
lensing spiral galaxies, for which multi-band high-resolution images and
rotation curves were obtained using the Hubble Space Telescope and Keck-II
Telescope as part of the Sloan WFC Edge-on Late-type Lens Survey (SWELLS). The
sample includes 8 newly discovered secure systems. [abridged] We find that the
SWELLS sample of secure lenses spans a broad range of morphologies (from
lenticular to late-type spiral), spectral types (quantified by Halpha
emission), and bulge to total stellar mass ratio (0.22-0.85), while being
limited to M_*>10^{10.5} M_sun. The SWELLS sample is thus well-suited for
exploring the relationship between dark and luminous matter in a broad range of
galaxies. We find that the deflector galaxies obey the same size-mass relation
as that of a comparison sample of elongated non-lens galaxies selected from the
SDSS survey. We conclude that the SWELLS sample is consistent with being
representative of the overall population of high-mass high-inclination disky
galaxies.Comment: 21 pages, 6 figures, MNRAS, in pres
A Lyman-alpha blob in the GOODS South field: evidence for cold accretion onto a dark matter halo
We report on the discovery of a z = 3.16 Lyman-alpha emitting blob in the
GOODS South field. The blob has a total Ly-alpha luminosity of ~ 10^(43) erg
s^(-1) and a diameter larger than 60 kpc. The available multi-wavelength data
in the GOODS field consists of 13 bands from X-rays (Chandra) to infrared
(Spitzer). Unlike other discovered Ly-alpha blobs, this blob shows no obvious
continuum counter-part in any of the broad-bands. In particular, no optical
counter-parts are found in the deep HST/ACS imaging available. For previously
published blobs, AGN (Active Galactic Nuclei) or 'superwind' models have been
found to provide the best match with the data. We here argue that the most
probable origin of the extended Ly-alpha emission from the blob in the GOODS
South field is cold accretion onto a dark matter halo.Comment: 4 pages, 2 tables, 2 figures, Accepted to A&A Letters, minor changes
to tex
NICMOS images of JVAS/CLASS gravitational lens systems
We present Hubble Space Telescope (HST) infrared images of four gravitational
lens systems from the JVAS/CLASS gravitational lens survey and compare the new
infrared HST pictures with previously published WFPC2 HST optical images and
radio maps. Apart from the wealth of information that we get from the flux
ratios and accurate positions and separations of the components of the lens
systems that we can use as inputs for better constraints on the lens models we
are able to discriminate between reddening and optical/radio microlensing as
the possible cause of differences observed in the flux ratios of the components
across the three wavelength bands. Substantial reddening has been known to be
present in the lens system B1600+434 and has been further confirmed by the
present infrared data. In the two systems B0712+472 and B1030+074 microlensing
has been pinpointed down as the main cause of the flux ratio discrepancy both
in the optical/infrared and in the radio, the radio possibly caused by the
substructure revealed in the lensing galaxies. In B0218+357 however the results
are still not conclusive. If we are actually seeing the two "true" components
of the lens system then the flux ratio differences are attributed to a
combination of microlensing and reddening or alternatively due to some
variability in at least one of the images. Otherwise the second "true"
component of B0218+357 maybe completely absorbed by a molecular cloud and the
anomalous flux density ratios and large difference in separation between the
optical/infrared and radio that we see can be explained by emission from either
a foreground object or from part of the lensing galaxy.Comment: 10 pages, 4 figures (original higher resolution figures can be
obtained at the e-mail above), to appear in MNRAS (accepted
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