5,887 research outputs found
Evidence for a Z < 8 Origin of the Source Subtracted Near Infrared Background
This letter extends our previous fluctuation analysis of the near infrared
background at 1.6 microns to the 1.1 micron (F110W) image of the Hubble Ultra
Deep field. When all detectable sources are removed the ratio of fluctuation
power in the two images is consistent with the ratio expected for faint, z<8,
sources, and is inconsistent with the expected ratio for galaxies with z>8. We
also use numerically redshifted model galaxy spectral energy distributions for
50 and 10 million year old galaxies to predict the expected fluctuation power
at 3.6 microns and 4.5 microns to compare with recent Spitzer observations. The
predicted fluctuation power for galaxies at z = 0-12 matches the observed
Spitzer fluctuation power while the predicted power for z>13 galaxies is much
higher than the observed values. As was found in the 1.6 micron (F160W)
analysis the fluctuation power in the source subtracted F110W image is two
orders of magnitude below the power in the image with all sources present. This
leads to the conclusion that the 0.8--1.8 micron near infrared background is
due to resolved galaxies in the redshift range z<8, with the majority of power
in the redshift range of 0.5--1.5.Comment: Accepted for publication in the Astrophysical Journa
Tracing the evolution of research in The Accounting Review through its leading authors: The 1946-1965 period
n order to better understand the development of accounting research, this paper examines the work of the leading authors of The Accounting Review (Leading Authors) during 1946-1965. An earlier study [Fleming, Graci and Thompson, 1990] concluded that the work of the Leading Authors during the 1926-1945 period was characterized by a practical orientation. The Accounting Review in many respects remained a practically oriented journal during 1946-1965. However, changes are evident that were contributing factors in the evolution of The Accounting Review into its current quantitative/empirical orientation
Characteristics of the work of leading authors of the Accounting Review, 1926-1945
The Accounting Review has changed dramatically over the years. The purpose of this study is to document these changes, putting into perspective the articles that are currently published in The Accounting Review. In particular, this study compares the work of those authors who had the most publications in The Accounting Review (Leading Authors) during 1926-1945 with more recent contributions. The results with respect to topic of articles, research methods, citations, and article length reflect the Leading Authors\u27 practical orientation, an attribute that is not particularly apparent in the work of current authors
A non-inertial two-phase model of wax transport in a pipeline during pigging operations
The removal of wax deposit from pipelines is commonly accomplished using pigs. In order to avoid the formation of wax plugs in pipes, bypass pigs, which create a liquid jet to disperse the scraped deposit, are employed. Despite many One-Dimensional (1D) models have been developed to predict the dynamics of bypass pigs, the details of the interaction between the liquid jet and the debris have not been investigated numerically yet. In this work the fluid dynamics of a wax-in-oil slurry in front of a moving bypass pig is studied by means of three-dimensional (3D) numerical simulations. A mathematical model which couples the pig and the wax-in-oil slurry dynamics, solved in the pig frame of reference, has been developed. The results show that the pig quickly reaches an equilibrium velocity, and the pig acceleration is proportional to the square of the mixture relative velocity. Comparing the present with previous sealing-pig results it appears that the bypass flow is more effective in deterring plug formation. Moreover, the 3D fields have the advantage of showing the wax distribution in each pipe section whereas the 1D model cannot distinguish between deposited and suspended wax
UK Competitiveness Index 2016
This 2016 edition of the UK Competitiveness Index (UKCI) represents a benchmarking of the competitiveness of the UK’s localities, including its cities, and Local Enterprise Partnership (LEP) areas and the equivalent city regions in the devolved regions of Wales and Scotland
Delayed Photoionization Feedback in a Super Star Cluster in SBS0335-052E
SBS0335-052 is a well studied Blue Compact Dwarf galaxy with one of the
lowest metallicities of any known galaxy. It also contains 6 previously
identified Super Star Clusters. We combine archival HST NICMOS images in the Pa
alpha line and the 1.6 micron continuum of the eastern component, SBS0335-052E,
with other space and ground based data to perform a multi-wavelength analysis
of the super star clusters. We concentrate on the southern most clusters,
designated S1 and S2, which appear to be the youngest clusters and are the
strongest emitters of Pa alpha, radio, and x-ray flux. Our analysis leads to a
possible model for S1 and perhaps S2 as a cluster of very young, massive stars
with strong stellar winds. The wind density can be high enough to absorb the
majority of ionizing photons within less than 1000 AU of the stars, creating
very compact HII regions that emit optically thick radiation at radio
wavelengths. These winds would then effectively quench the photoionizing flux
very close to the stars. This can delay the onset of negative feedback by
photoionization and photodissociation on star formation in the clusters. This
is significant since SBS0335-052E resembles the conditions that were probably
common for high redshift star formation in galaxies near the epoch of
reionization.Comment: Accepted for publication in the Astrophysical Journa
Simulator of Galaxy Millimeter/Submillimeter Emission (SIGAME): The [CII]-SFR Relationship of Massive z=2 Main Sequence Galaxies
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