1,471 research outputs found
Measuring the competitiveness of the UK construction industry. Volume 1
EBSâs estimates of relative productivity in construction are as follows:
1.
The US is about 25-35% ahead of the UK and Germany in terms of average labour productivity (ALP).
2.
The UK is ahead of Germany in ALP on an output per worker basis, but not on an output per hour worked basis (this is due to Germans working fewer hours per week on average).
These results are largely unchanged under various sensitivity tests, for example, using GDP PPP exchange rates instead of construction PPP exchange rates to convert national currencies to a common currency.
The EBS estimate for the US-UK comparison is supported by UCL/DL (who estimate a US lead in ALP of 42% in 1999).
UCL/DLâs estimates for the Germany-UK comparison are also similar to those of EBS, since they show Germany level with the UK in ALP on an output per worker basis, but ahead on an output per hour worked basis.
Productivity comparisons of the UK with France are subject to difficulties. Depending on the exchange rates they use for conversion purposes, EBS find that France is well ahead of Britain on some measures of ALP (and indeed is close to the US) but on other measures French ALP is much the same as in Britain.
UCL/DL argue strongly for using an exchange rate, which shows French construction ALP to be well ahead of the UK. They state that: âThe French construction PPPs have been controversial for some timeâŠ.[and tend to lead to] underestimates of French construction outputâ.
There are difficulties in conducting this type of analysis that are hard to surmount, for example it is unlikely that labour inputs are well measured in any country because of illegal immigration, â the hidden economyâ, etc. However, unless there is reason to think that the proportion of uncounted construction workers is significantly higher or lower in Britain as compared to, say, the United States, then it seems reasonable to accept that ALP in the US construction industry is some way ahead of the UK.
In many ways cross-country comparisons of productivity levels across the whole construction industry are not comparing like with like since the composition of construction output differs greatly from country to country. It is therefore hard to construct reliable national rankings based on aggregated data for construction given the present state of the data
Early-time Spitzer observations of the type II-Plateau supernova, 2004dj
We present mid-infrared observations with the Spitzer Space Telescope of the
nearby type II-P supernova, SN 2004dj, at epochs of 89 to 129 days. We have
obtained the first mid-IR spectra of any supernova apart from SN 1987A. A
prominent [NiII] 6.64 micron line is observed, from which we deduce that the
mass of stable nickel must be at least 2.2e10(-4) Msun. We also observe the red
wing of the CO-fundamental band. We relate our findings to possible progenitors
and favour an evolved star, most likely a red supergiant, with a probable
initial mass between ~10 and 15 Msun.Comment: ApJ Letters (accepted
A Spitzer Space Telescope study of SN 2002hh: an infrared echo from a Type IIP supernova
We present late-time (590-994 d) mid-IR photometry of the normal, but
highly-reddened Type IIP supernova SN 2002hh. Bright, cool, slowly-fading
emission is detected from the direction of the supernova. Most of this flux
appears not to be driven by the supernova event but instead probably originates
in a cool, obscured star-formation region or molecular cloud along the
line-of-sight. We also show, however, that the declining component of the flux
is consistent with an SN-powered IR echo from a dusty progenitor CSM. Mid-IR
emission could also be coming from newly-condensed dust and/or an ejecta/CSM
impact but their contributions are likely to be small. For the case of a CSM-IR
echo, we infer a dust mass of as little as 0.036 M(solar) with a corresponding
CSM mass of 3.6(0.01/r(dg))M(solar) where r(dg) is the dust-to-gas mass ratio.
Such a CSM would have resulted from episodic mass loss whose rate declined
significantly about 28,000 years ago. Alternatively, an IR echo from a
surrounding, dense, dusty molecular cloud might also have been responsible for
the fading component. Either way, this is the first time that an IR echo has
been clearly identified in a Type IIP supernova. We find no evidence for or
against the proposal that Type IIP supernovae produce large amounts of dust via
grain condensation in the ejecta. However, within the CSM-IR echo scenario, the
mass of dust derived implies that the progenitors of the most common of
core-collapse supernovae may make an important contribution to the universal
dust content.Comment: 41 pages, 11 figures, 4 tables, accepted for publication in
Astrophysical Journal (References corrected
The Rise Times of High and Low Redshift Type Ia Supernovae are Consistent
We present a self-consistent comparison of the rise times for low- and
high-redshift Type Ia supernovae. Following previous studies, the early light
curve is modeled using a t-squared law, which is then mated with a modified
Leibundgut template light curve. The best-fit t-squared law is determined for
ensemble samples of low- and high-redshift supernovae by fitting simultaneously
for all light curve parameters for all supernovae in each sample. Our method
fully accounts for the non-negligible covariance amongst the light curve
fitting parameters, which previous analyses have neglected. Contrary to Riess
et al. (1999), we find fair to good agreement between the rise times of the
low- and high-redshift Type Ia supernovae. The uncertainty in the rise time of
the high-redshift Type Ia supernovae is presently quite large (roughly +/- 1.2
days statistical), making any search for evidence of evolution based on a
comparison of rise times premature. Furthermore, systematic effects on rise
time determinations from the high-redshift observations, due to the form of the
late-time light curve and the manner in which the light curves of these
supernovae were sampled, can bias the high-redshift rise time determinations by
up to +3.6/-1.9 days under extreme situations. The peak brightnesses - used for
cosmology - do not suffer any significant bias, nor any significant increase in
uncertainty.Comment: 18 pages, 4 figures, Accepted for publication in the Astronomical
Journal. Also available at http://www.lbl.gov/~nugent/papers.html Typos were
corrected and a few sentences were added for improved clarit
Using scaling-region distributions to select embedding parameters
Reconstructing state-space dynamics from scalar data using time-delay
embedding requires choosing values for the delay and the dimension .
Both parameters are critical to the success of the procedure and neither is
easy to formally validate. While embedding theorems do offer formal guidance
for these choices, in practice one has to resort to heuristics, such as the
average mutual information (AMI) method of Fraser & Swinney for or the
false near neighbor (FNN) method of Kennel et al. for . Best practice
suggests an iterative approach: one of these heuristics is used to make a good
first guess for the corresponding free parameter and then an "asymptotic
invariant" approach is then used to firm up its value by, e.g., computing the
correlation dimension or Lyapunov exponent for a range of values and looking
for convergence. This process can be subjective, as these computations often
involve finding, and fitting a line to, a scaling region in a plot: a process
that is generally done by eye and is not immune to confirmation bias. Moreover,
most of these heuristics do not provide confidence intervals, making it
difficult to say what "convergence" is. Here, we propose an approach that
automates the first step, removing the subjectivity, and formalizes the second,
offering a statistical test for convergence. Our approach rests upon a recently
developed method for automated scaling-region selection that includes
confidence intervals on the results. We demonstrate this methodology by
selecting values for the embedding dimension for several real and simulated
dynamical systems. We compare these results to those produced by FNN and
validate them against known results -- e.g., of the correlation dimension --
where these are available. We note that this method extends to any free
parameter in the theory or practice of delay reconstruction
What lies beneath? The role of informal and hidden networks in the management of crises
Crisis management research traditionally focuses on the role of formal communication networks in the escalation and management of organisational crises. Here, we consider instead informal and unobservable networks. The paper explores how hidden informal exchanges can impact upon organisational decision-making and performance, particularly around inter-agency working, as knowledge distributed across organisations and shared between organisations is often shared through informal means and not captured effectively through the formal decision-making processes. Early warnings and weak signals about potential risks and crises are therefore often missed. We consider the implications of these dynamics in terms of crisis avoidance and crisis management
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