27,347 research outputs found
Cosmological Parameters from the Comparison of the 2MASS Gravity Field with Peculiar Velocity Surveys
We compare the peculiar velocity field within 65 Mpc predicted from
2MASS photometry and public redshift data to three independent peculiar
velocity surveys based on type Ia supernovae, surface brightness fluctuations
in ellipticals, and Tully-Fisher distances to spirals. The three peculiar
velocity samples are each in good agreement with the predicted velocities and
produce consistent results for \beta_{K}=\Omega\sbr{m}^{0.6}/b_{K}. Taken
together the best fit . We explore the effects of
morphology on the determination of by splitting the 2MASS sample into
E+S0 and S+Irr density fields and find both samples are equally good tracers of
the underlying dark matter distribution, but that early-types are more
clustered by a relative factor b\sbr{E}/b\sbr{S} \sim 1.6. The density
fluctuations of 2MASS galaxies in Mpc spheres in the local volume is
found to be \sigma\sbr{8,K} = 0.9. From this result and our value of
, we find \sigma_8 (\Omega\sbr{m}/0.3)^{0.6} = 0.91\pm0.12. This
is in excellent agreement with results from the IRAS redshift surveys, as well
as other cosmological probes. Combining the 2MASS and IRAS peculiar velocity
results yields \sigma_8 (\Omega\sbr{m}^/0.3)^{0.6} = 0.85\pm0.05.Comment: 11 pages, ApJ accepte
A Test for Large-Scale Systematic Errors in Maps of Galactic Reddening
Accurate maps of Galactic reddening are important for a number of
applications, such as mapping the peculiar velocity field in the nearby
Universe. Of particular concern are systematic errors which vary slowly as a
function of position on the sky, as these would induce spurious bulk flow. We
have compared the reddenings of Burstein & Heiles (BH) and those of Schlegel,
Finkbeiner & Davis (SFD) to independent estimates of the reddening, for
Galactic latitudes |b| > 10. Our primary source of Galactic reddening estimates
comes from comparing the difference between the observed B-V colors of
early-type galaxies, and the predicted B-V color determined from the B-V--Mg_2
relation. We have fitted a dipole to the residuals in order to look for
large-scale systematic deviations. There is marginal evidence for a dipolar
residual in the comparison between the SFD maps and the observed early-type
galaxy reddenings. If this is due to an error in the SFD maps, then it can be
corrected with a small (13%) multiplicative dipole term. We argue, however,
that this difference is more likely to be due to a small (0.01 mag.) systematic
error in the measured B-V colors of the early-type galaxies. This
interpretation is supported by a smaller, independent data set (globular
cluster and RR Lyrae stars), which yields a result inconsistent with the
early-type galaxy residual dipole. BH reddenings are found to have no
significant systematic residuals, apart from the known problem in the region
230 < l < 310, -20 < b < 20.Comment: 8 pages, PASP, in press (Jan 1999
Workplaces in the cinema
Purpose â The purpose of this paper is to explore the representation of workplaces in the cinema and discuss its relevance to facilities management research.
Design/methodology/approach â An analysis of representation of work and the workplace in three films is made. These are Metropolis (1927), Wall Street (1987) and Clerks (1994). Cross-case themes are then discussed.
Findings â Although the three films are of different time periods and genres a number of common themes emerge. These include level of control over the work process, alienation from the product of work and social capital gained. This may have implications for how workplaces are perceived and interpreted. Analysis of representations of the workplace in popular culture may contribute to user-centred approaches to facilities management.
Research limitations/implications â The study is limited to three films. A different choice might produce different results.
Practical implications â Understanding representations of the workplace in popular culture may give insights into user responses to management actions.
Originality/value â Although there is a research literature on the analysis of popular culture within organizational studies this has not been taken up by facilities management researchers. This paper explores the relevance of the analysis of an aspect of popular culture for facilities management
The Peculiar Velocities of Local Type Ia Supernovae and their Impact on Cosmology
We quantify the effect of supernova Type Ia peculiar velocities on the
derivation of cosmological parameters. The published distant and local Ia SNe
used for the Supernova Legacy Survey first-year cosmology report form the
sample for this study. While previous work has assumed that the local SNe are
at rest in the CMB frame (the No Flow assumption), we test this assumption by
applying peculiar velocity corrections to the local SNe using three different
flow models. The models are based on the IRAS PSCz galaxy redshift survey, have
varying beta = Omega_m^0.6/b, and reproduce the Local Group motion in the CMB
frame. These datasets are then fit for w, Omega_m, and Omega_Lambda using
flatness or LambdaCDM and a BAO prior. The chi^2 statistic is used to examine
the effect of the velocity corrections on the quality of the fits. The most
favored model is the beta=0.5 model, which produces a fit significantly better
than the No Flow assumption, consistent with previous peculiar velocity
studies. By comparing the No Flow assumption with the favored models we derive
the largest potential systematic error in w caused by ignoring peculiar
velocities to be Delta w = +0.04. For Omega_Lambda, the potential error is
Delta Omega_Lambda = -0.04 and for Omega_m, the potential error is Delta
Omega_m < +0.01. The favored flow model (beta=0.5) produces the following
cosmological parameters: w = -1.08 (+0.09,-0.08), Omega_m = 0.27 (+0.02,-0.02)
assuming a flat cosmology, and Omega_Lambda = 0.80 (+0.08,-0.07) and Omega_m =
0.27 (+0.02,-0.02) for a w = -1 (LambdaCDM) cosmology.Comment: 4 pages, 2 figures, 1 table, accepted for publication in ApJ Letter
Aid Volatility, Policy and Development
We build on Bulir and Hamann's analysis of aid volatility (2003, 2005), showing that the conclusions reached depend on the dataset used. Their argument that the poorest countries have the highest volatility appears not to be correct. The impact of volatility on growth is negative overall, but differs between positive and negative volatility. The mix between `responsive´ components of aid, e.g. programme aid, and `proactive´ components, e.g. technical assistance, is important. Finally, we conclude that measures which increase trust between donor and recipient, and reductions in the degree of donor `oligopoly´, reduce aid volatility without obviously reducing its effectiveness
Spatial nucleation and crystal growth Final report, 1 Jun. 1964 - 30 Sep. 1967
Nucleation and growth processes in interstellar grain formatio
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