97 research outputs found
Improving IS Service Quality
The growth of end-user computing has led to an awareness of the need to evaluate the quality of services provided by the information systems function. This paper discusses the two primary schools of thought or approaches concerning service quality. While the disconfirmation-based approach conceptualizes service quality as âsimilar to an attitude, the performance-based approach conceptualizes service quality as âattitude-based.â The literature concerning the application of both service quality approaches in an IS context are discussed and analyzed. Special attention is paid to the service orientation of IS employees as they relate to IS users. Prescriptions for improvements to the quality of IS service are suggested in four management areas: 1) service orientation of IS providers, 2) training/education of IS providers and IS users, 3) reward system for IS employees, and 4) linking IT strategy to business strategy. Lastly, SERVQUAL and SERVPERF are discussed as two quantitative measures of IS service quality
Using Distributive Justice Theory to Examine Job Stability Outcomes of IT Professionals during a Down Labor Market
The Millennium Galaxy Catalogue: 16 < B_MGC < 24 galaxy counts and the calibration of the local galaxy luminosity function
The Millennium Galaxy Catalogue (MGC) is a 37.5 deg^2, medium-deep, B-band
imaging survey along the celestial equator, taken with the Wide Field Camera on
the Isaac Newton Telescope. The survey region is contained within the regions
of both the Two Degree Field Galaxy Redshift Survey (2dFGRS) and the Sloan
Digital Sky Survey Early Data Release (SDSS-EDR). The survey has a uniform
isophotal detection limit of 26 mag arcsec^-2 and it provides a robust,
well-defined catalogue of stars and galaxies in the range 16 <= B_MGC < 24 mag.
Here we describe the survey strategy, the photometric and astrometric
calibration, source detection and analysis, and present the galaxy number
counts that connect the bright and faint galaxy populations within a single
survey. We argue that these counts represent the state of the art and use them
to constrain the normalizations (phi*) of a number of recent estimates of the
local galaxy luminosity function. We find that the 2dFGRS, SDSS Commissioning
Data (CD), ESO Slice Project, Century Survey, Durham/UKST, Mt Stromlo/APM,
SSRS2, and NOG luminosity functions require a revision of their published phi*
values by factors of 1.05 +/- 0.05, 0.76 +/- 0.10, 1.02 +/- 0.22, 1.02 +/-
0.16, 1.16 +/- 0.28, 1.75 +/- 0.37, 1.40 +/- 0.26 and 1.01 +/- 0.39,
respectively. After renormalizing the galaxy luminosity functions we find a
mean local \bj luminosity density of j_{b_J} = (1.986 +/- 0.031) x 10^8 h
L_{\odot} Mpc^-3.Comment: 20 pages, LaTeX, 20 Postscript figures (some low resolution), MNRAS,
in press; considerably revised versio
Galaxy Colour, Morphology, and Environment in the Sloan Digital Sky Survey
We use the Fourth Data Release of the Sloan Digital Sky Survey to investigate
the relation between galaxy rest frame u-r colour, morphology, as described by
the concentration and Sersic indices, and environmental density, for a sample
of 79,553 galaxies at z < ~0.1. We split the samples according to density and
luminosity and recover the expected bimodal distribution in the
colour-morphology plane, shown especially clearly by this subsampling. We
quantify the bimodality by a sum of two Gaussians on the colour and morphology
axes and show that, for the red/early-type population both colour and
morphology do not change significantly as a function of density. For the
blue/late-type population, with increasing density the colour becomes redder
but the morphology again does not change significantly. Both populations become
monotonically redder and of earlier type with increasing luminosity. There is
no significant qualitative difference between the behaviour of the two
morphological measures. We supplement the morphological sample with 13,655
galaxies assigned Hubble types by an artificial neural network. We find,
however, that the resulting distribution is less well described by two
Gaussians. Therefore, there are either more than two significant morphological
populations, physical processes not seen in colour space, or the Hubble type,
particularly the different subtypes of spirals Sa-Sd, has an irreducible
fuzziness when related to environmental density. For each of the three measures
of morphology, on removing the density relation due to it, we recover a strong
residual relation in colour. However, on similarly removing the colour-density
relation there is no evidence for a residual relation due to morphology.
[Abridged]Comment: Substantial revision to match MNRAS accepted version. Overall
conclusions unchanged. 16 pages, 13 figure
The physical properties of star forming galaxies in the low redshift universe
(modified) We present a comprehensive study of the physical properties of
\~10^5 galaxies with measurable star formation in the SDSS. By comparing
physical information extracted from the emission lines with continuum
properties, we build up a picture of the nature of star-forming galaxies at
z<0.2. We take out essentially all aperture bias using resolved imaging,
allowing an accurate estimate of the total SFRs in galaxies. We determine the
SFR density to be 1.915^{+0.02}_{-0.01}(rand.)^{+0.14}_{-0.42} (sys.) h70
10^{-2} Msun/yr/Mpc^3 at z=0.1 (for a Kroupa IMF) and we study the distribution
of star formation as a function of various physical parameters. The majority of
the star formation in the low redshift universe takes place in moderately
massive galaxies (10^10-10^11 Msun), typically in HSB disk galaxies. Roughly
15% of all star formation takes place in galaxies that show some sign of an
active nucleus. About 20% occurs in starburst galaxies. We show that the
present to past-average star formation rate, the Scalo b-parameter; is almost
constant over almost three orders of magnitude in mass, declining only at
M*>10^10 Msun. The volume averaged b parameter is 0.408^{+0.005}_{-0.002}
(rand).^{+0.029}_{-0.090} (sys.) h70^{-1}. We use this value constrain the star
formation history of the universe. In agreement with other work we find a
correlation between and morphological type, as well as a tight correlation
between the 4000AA break (D4000) and b. We discuss how D4000 can be used to
estimate b parameters for high redshift galaxies.Comment: Accepted for MNRAS. Replaced with accepted version. A section on
comparison with other methods of SFR estimation added and various updates
have been made. The main results are almost unchange
Revealing components of the galaxy population through nonparametric techniques
The distributions of galaxy properties vary with environment, and are often
multimodal, suggesting that the galaxy population may be a combination of
multiple components. The behaviour of these components versus environment holds
details about the processes of galaxy development. To release this information
we apply a novel, nonparametric statistical technique, identifying four
components present in the distribution of galaxy H emission-line
equivalent-widths. We interpret these components as passive, star-forming, and
two varieties of active galactic nuclei. Independent of this interpretation,
the properties of each component are remarkably constant as a function of
environment. Only their relative proportions display substantial variation. The
galaxy population thus appears to comprise distinct components which are
individually independent of environment, with galaxies rapidly transitioning
between components as they move into denser environments.Comment: 12 pages, 10 figures, accepted for publication in MNRA
A Mismatch in the Ultraviolet Spectra between Low-Redshift and Intermediate-Redshift Type Ia Supernovae as a Possible Systematic Uncertainty for Supernova Cosmology
We present Keck high-quality rest-frame ultraviolet (UV) through optical
spectra of 21 Type Ia supernovae (SNe Ia) in the redshift range 0.11 < z < 0.37
and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky
Survey-II (SDSS-II) SN Survey. Using the broad-band photometry of the SDSS
survey, we are able to reconstruct the SN host-galaxy spectral energy
distributions (SEDs), allowing for a correction for the host-galaxy
contamination in the SN Ia spectra. Comparison of composite spectra constructed
from a subsample of 17 high-quality spectra to those created from a
low-redshift sample with otherwise similar properties shows that the Keck/SDSS
SNe Ia have, on average, extremely similar rest-frame optical spectra but show
a UV flux excess. This observation is confirmed by comparing synthesized
broad-band colors of the individual spectra, showing a difference in mean
colors at the 2.4 - 4.4 sigma level for various UV colors. We further see a
slight difference in the UV spectral shape between SNe with low-mass and
high-mass host galaxies. Additionally, we detect a relationship between the
flux ratio at 2770 and 2900 A and peak luminosity that differs from that
observed at low redshift. We find that changing the UV SED of an SN Ia within
the observed dispersion can change the inferred distance moduli by ~0.1 mag.
This effect only occurs when the data probe the rest-frame UV. We suggest that
this discrepancy could be due to differences in the host-galaxy population of
the two SN samples or to small-sample statistics.Comment: 28 pages, 21 figures, accepted by AJ, spectra are available at
http://www.cfa.harvard.edu/~rfoley/data
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