1,237 research outputs found
THE RANGE AND ROLE OF THEORY IN INFORMATION SYSTEMS DESIGN RESEARCH: FROM CONCEPTS TO CONSTRUCTION
This paper reports results from a field study of cross-disciplinary design researchers in information systems, software engineering, human-computer interaction, and computer-supported cooperative work. The purpose of the study was to explore how these different disciplines conceptualize and conduct design-as-research. The focus in this paper is on how theories are used in a design research project to motivate and inform the particulars of designed artifacts and design methods. Our objective was to better understand how elements of a theory are translated into design action, and how theoretical propositions are translated and then realized in designed artifacts. The results reveal a broad diversity in the processes through which theories are translated into working artifacts. The paper contributes to our understanding of design research in information systems by providing empirical support for existing constructs and frameworks, identifying some new approaches to translating theoretical concepts into research designs, and suggesting ways in which action and artifact-oriented research can more effectively contribute to a cumulative and progressive science of design
Identifying galaxy candidates in WSRT HI imaging of ultra-compact high velocity clouds
Ultra-compact high velocity clouds (UCHVCs) were identified in the ALFALFA HI
survey as potential gas-bearing dark matter halos. Here we present higher
resolution neutral hydrogen (HI) observations of twelve UCHVCS with the
Westerbork Synthesis Radio Telescope (WSRT). The UCHVCs were selected based on
a combination of size, isolation, large recessional velocity and high column
density as the best candidate dark matter halos. The WSRT data were tapered to
image the UCHVCs at 210" (comparable to Arecibo) and 105" angular resolution.
In a comparison of the single-dish to interferometer data, we find that the
line flux recovered in the WSRT observations is comparable to that from the
single-dish ALFALFA data. In addition, any structure seen in the ALFALFA data
is reproduced in the WSRT maps at the same angular resolution. At 210'"
resolution all the sources are generally compact with a smooth HI morphology,
as expected from their identification as UCHVCs. At the higher angular
resolution, a majority of the sources break into small clumps contained in a
diffuse envelope. These UCHVCs also have no ordered velocity motion and are
most likely Galactic halo clouds. We identify two UCHVCs, AGC 198606 and AGC
249525, as excellent galaxy candidates based on maintaining a smooth HI
morphology at higher angular resolution and showing ordered velocity motion
consistent with rotation. A third source, AGC 249565, lies between these two
populations in properties and is a possible galaxy candidate. If interpreted as
gas-bearing dark matter halos, the three candidate galaxies have rotation
velocities of 8-15 km/s, HI masses of 0.6-50 x 10^5 Msun, HI radii of 0.3-2
kpc, and dynamical masses of 2-20 x 10^7 Msun for a range of plausible
distances. These are the UCHVCs with the highest column density values in the
ALFALFA HI data and we suggest this is the best way to identify further
candidates.Comment: Accepted for publication in A&A. 26 pages, 19 figures, 5 table
HI Emission and Absorption in the Southern Galactic Plane Survey
We present preliminary results from the Southern Galactic Plane Survey (SGPS)
Test Region and Parkes data. As part of the pilot project for the Southern
Galactic Plane Survey, observations of a Test Region (325.5 deg < l < 333.5
deg; -0.5 deg < b < 3.5 deg) were completed in December 1998. Single dish
observations of the full survey region (253 deg < l < 358 deg; |b| <1 deg) with
the Parkes Radio Telescope were completed in March 2000. We present a sample of
SGPS HI data with particular attention to the smallest and largest scale
structures seen in absorption and emission, respectively. On the large scale,
we detect many prominent HI shells. On the small scale, we note extremely
compact, cold clouds seen in HI self-absorption. We explore how these two
classes of objects probe opposite ends of the HI spatial power spectrum.Comment: 9 pages, 3 embedded postscript & 4 jpeg figures. Presented at the
Astronomical Society of Australia, Hobart, Tasmania, July 4-7 2000. To appear
in PASA Vol. 18(1
Detection of an Optical Counterpart to the ALFALFA Ultra-compact High Velocity Cloud AGC 249525
We report on the detection at 98% confidence of an optical counterpart to
AGC 249525, an Ultra-Compact High Velocity Cloud (UCHVC) discovered by the
ALFALFA blind neutral hydrogen survey. UCHVCs are compact, isolated HI clouds
with properties consistent with their being nearby low-mass galaxies, but
without identified counterparts in extant optical surveys. Analysis of the
resolved stellar sources in deep - and -band imaging from the WIYN pODI
camera reveals a clustering of possible Red Giant Branch stars associated with
AGC 249525 at a distance of 1.640.45 Mpc. Matching our optical detection
with the HI synthesis map of AGC 249525 from Adams et al. (2016) shows that the
stellar overdensity is exactly coincident with the highest-density HI contour
from that study. Combining our optical photometry and the HI properties of this
object yields an absolute magnitude of , a stellar
mass between and , and an HI to stellar mass ratio between 9 and 144. This object has
stellar properties within the observed range of gas-poor Ultra-Faint Dwarfs in
the Local Group, but is gas-dominated.Comment: 9 pages, 4 figures; accepted to ApJ
Lifetime and Coherence of Two-Level Defects in a Josephson Junction
We measure the lifetime () and coherence () of two-level defect
states (TLSs) in the insulating barrier of a Josephson phase qubit and compare
to the interaction strength between the two systems. We find for the average
decay times a power law dependence on the corresponding interaction strengths,
whereas for the average coherence times we find an optimum at intermediate
coupling strengths. We explain both the lifetime and the coherence results
using the standard TLS model, including dipole radiation by phonons and
anti-correlated dependence of the energy parameters on environmental
fluctuations.Comment: 4 pages, 4 figures and supplementary material (3 pages, 2 figures, 1
table
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