2,620 research outputs found
Interrupting the social amplification of risk process: a case study in collective emissions reduction
One of the main approaches we have for studying the progressive divergence of understandings around a risk issue is that of social risk amplification. This article describes a case study of a particular environmental contaminant, a chemical flame retardant that could be interpreted as having produced a risk amplifying process. It describes in particular how a group of industrial organizations acted collectively to reduce emissions of this contaminant, in an apparent attempt to avert regulation and boycottsâthat is, to intercept the social amplification process and avoid its secondary effects. The aim of the study was to investigate the constitutive qualities of this collective action: the qualities that defined it and made it effective in the eyes of those involved. These include institutionalisation and independence, the ability to confer individual as well as collective benefit, the capacity to attract (rather than avoid) criticism, and the âbrandingâ that helps communicate what otherwise appear to be a set of unconnected, local actions. Although the risk amplification framework has been criticised for implying that there is some externally given risk level that is subsequently amplified, it does appear to capture the mentality of actors involved in issues of this kind. They talk and act as though they believe they are participants in a risk amplification process
Early production of the passive in two Eastern Bantu languages
The passive construction is acquired relatively late by children learning to speak many languages, with verbal passives not fully acquired till age 6 in English. In other languages it appears earlier, around age 3 or before. Use of passive construction in young children was examined in two Eastern Bantu languages spoken in Kenya (Kiswahili and Kigiriama), both with frequent use of passive. The passive was used productively very early (2;1) in these languages, regardless of the method used to measure productivity. In addition non-actional passives, particularly rare in English and some other European languages, were seen at these early ages. The proportion of verbs that were passive varied between individuals, both in children's speech and in the input to children. Pragmatic and grammatical features of the passive in some languages have previously been suggested to drive early passive acquisition, but these features are not found consistently in the two languages studied here. Findings suggest that the relatively high frequency of input found in these languages is the most plausible reason for early productive use of the passive
AX J0049.4-7323 - a close look at a neutron star interacting with a circumstellar disk
Detailed evidence on the system AX J0049.4-7323 is presented here to show how
the passage of the neutron star in the binary system disrupts the circumstellar
disk of the mass donor Be star. A similar effect is noted in three other
Be/X-ray binary systems. Together the observational data should provide
valuable tools for modelling these complex interactions.Comment: 4 pages, accepted for publication in MNRA
Large-Scale Bulk Motions Complicate the Hubble Diagram
We investigate the extent to which correlated distortions of the luminosity
distance-redshift relation due to large-scale bulk flows limit the precision
with which cosmological parameters can be measured. In particular, peculiar
velocities of type 1a supernovae at low redshifts may prevent a sufficient
calibration of the Hubble diagram necessary to measure the dark energy equation
of state to better than 10%, and diminish the resolution of the equation of
state time-derivative projected for planned surveys. We consider similar
distortions of the angular-diameter distance, as well as the Hubble constant.
We show that the measurement of correlations in the large-scale bulk flow at
low redshifts using these distance indicators may be possible with a cumulative
signal-to-noise ratio of order 7 in a survey of 300 type 1a supernovae spread
over 20,000 square degrees.Comment: 6 pages; 4 figure
Design practices used in the development of microfluidic devices: a services-based view
This paper presents the current state of microfluidic design from a practitionerâs perspective. The capture of microfluidic design practice was facilitated through a combination of industry survey and expert interviews, allowing the authors to draw out models for microfluidic design. Exploration of the current practice of microfluidic design showed that formal design methodologies were not in use. This research has also found that sub-section interactions have been addressed in an inadequate fashion by current design practices. The work presented in this paper outlines the scope for further research in the development of a formal design methodology for microfluidics
A major outburst from the X-ray binary RX J0520.5-6932
We report on the analysis of 8 years of MAssive Compact Halo Objects (MACHO)
data for the source RX J0520.5-6932. A regular period of 24.4 days has been
confirmed, however this is manifest almost entirely in the red part of the
spectrum. A major outburst, lasting approximately 200 days, was observed which
increased the apparent brightness of the object by approximately 0.15
magnitudes without significantly altering its V-R colour index. This outburst
was also seen in X-ray data. The evidence from this analysis points to the
identification of this object as a Be/X-ray binary with a periodically variable
circumstellar disk and a very early optical counterpart.Comment: Paper has been accepted by MNRA
A Proper Motion Survey for White Dwarfs with the Wide Field Planetary Camera 2
We have performed a search for halo white dwarfs as high proper motion
objects in a second epoch WFPC2 image of the Groth-Westphal strip. We identify
24 high proper motion objects with mu > 0.014 ''/yr. Five of these high proper
motion objects are identified as strong white dwarf candidates on the basis of
their position in a reduced proper motion diagram. We create a model of the
Milky Way thin disk, thick disk and stellar halo and find that this sample of
white dwarfs is clearly an excess above the < 2 detections expected from these
known stellar populations. The origin of the excess signal is less clear.
Possibly, the excess cannot be explained without invoking a fourth galactic
component: a white dwarf dark halo. We present a statistical separation of our
sample into the four components and estimate the corresponding local white
dwarf densities using only the directly observable variables, V, V-I, and mu.
For all Galactic models explored, our sample separates into about 3 disk white
dwarfs and 2 halo white dwarfs. However, the further subdivision into the thin
and thick disk and the stellar and dark halo, and the subsequent calculation of
the local densities are sensitive to the input parameters of our model for each
Galactic component. Using the lowest mean mass model for the dark halo we find
a 7% white dwarf halo and six times the canonical value for the thin disk white
dwarf density (at marginal statistical significance), but possible systematic
errors due to uncertainty in the model parameters likely dominate these
statistical error bars. The white dwarf halo can be reduced to around 1.5% of
the halo dark matter by changing the initial mass function slightly. The local
thin disk white dwarf density in our solution can be made consistent with the
canonical value by assuming a larger thin disk scaleheight of 500 pc.Comment: revised version, accepted by ApJ, results unchanged, discussion
expande
Gravitational Waves from Sub-lunar Mass Primordial Black Hole Binaries - A New Probe of Extradimensions
In many braneworld models, gravity is largely modified at the electro-weak
scale ~ 1TeV. In such models, primordial black holes (PBHs) with lunar mass M ~
10^{-7}M_sun might have been produced when the temperature of the universe was
at ~ 1TeV. If a significant fraction of the dark halo of our galaxy consists of
these lunar mass PBHs, a huge number of BH binaries will exist in our
neighborhood. Third generation detectors such as EURO can detect gravitational
waves from these binaries, and can also determine their chirp mass. With a new
detector designed to be sensitive at high frequency bands greater than 1 kHz,
the existence of extradimensions could be confirmed.Comment: 4 pages, 1 figure, typos correcte
X-Ray Off States and Optical Variability in CAL 83
CAL 83 was one of the first supersoft X-ray binaries to be discovered and is
considered to be the prototype of its class. In 15 X-ray observations between
1983-1997 it was observed to have nearly constant X-ray luminosity and
temperature, with the exception of one off-state in 1996. We report on a second
X-ray off-state, discovered with a Chandra ACIS-S observation in November 1999.
Comparing the long-term X-ray and MACHO optical light curves, we find that, CAL
83 has exhibited distinct and well-defined low, intermediate, and high optical
states. Transitions between states are not accompanied by color variations.
Both X-ray off states were observed during optical high states and were
followed by optical low states within ~50 days. We discuss possible
explanations for the observed optical and X-ray variations.Comment: 12 pages A&A style with 5 figures; accepted for publication in A&A
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