724 research outputs found
Interchanging Interactive 3-d Graphics for Astronomy
We demonstrate how interactive, three-dimensional (3-d) scientific
visualizations can be efficiently interchanged between a variety of mediums.
Through the use of an appropriate interchange format, and a unified interaction
interface, we minimize the effort to produce visualizations appropriate for
undertaking knowledge discovery at the astronomer's desktop, as part of
conference presentations, in digital publications or as Web content. We use
examples from cosmological visualization to address some of the issues of
interchange, and to describe our approach to adapting S2PLOT desktop
visualizations to the Web.
Supporting demonstrations are available at
http://astronomy.swin.edu.au/s2plot/interchange/Comment: 10 pages, 7 figures, submitted to Publications of the Astronomical
Society of Australia. v2. Revised title, revised figure 1, fixed typos, minor
additions to future work sectio
Perspectives On The Sources And Eventual Outcome Of The 2008 Economic And Financial Crisis: A Panel Discussion
In October 2008 the Southern Utah University School of Business held a panel discussion on the current economic crisis. This discussion was part of the Schoolâs Business Convocation series and was open to the public. The panel was designed with two components in mind. First, a pair of academics with expertise in financial institutions and business cycles offered historical and theoretical perspectives on the crisis. Second, a pair of professionals â a local banking official and a fund manager â offered perspectives on the current financial situation and practical experience based on the policy responses to past crises. As moderator, Joe Baker asked each panelist to make a short presentation on a question of general interest that was related to their area of expertise; this was followed by an open question and answer session. The participating panelists and opening questions follow. 1. Stephen Evans, Professor of Finance: Dr. Evans teaches courses on financial institutions and was asked to provide background of how the crisis occurred and what the proposed government bailout plan is expected to accomplish. 2. David Tufte, Associate Professor of Economics: Dr. Tufte is a macroeconomist and was asked to discuss the macroeconomic implications of the crisis in such areas as inflation, interest rates, economic growth and unemployment. 3. Mr. Robb Kerry, Chief Credit Officer of ADB Bank: Mr. Kerry has an extensive background in banking as a bank regulator and banker. Mr. Kerry was asked to discuss the implications of the crisis on banking credit and lending. Mr. Steve Harrop, Finance Professional in Residence: Mr. Harrop was a mutual fund manager for several decades before joining the School of Business faculty where he teaches investments and manages (pro bono) an investment fund. Mr. Harrop will discuss the implications of the crisis on the stock and bond markets
Observations of the Extended Distribution of Ionized Hydrogen in the Plane of M31
We have used the Wisconsin H-Alpha Mapper (WHAM) to observe the spatially
extended distribution of ionized hydrogen in M31 beyond the stellar disk. We
obtained five sets of observations, centered near the photometric major axis of
M31, that extend from the center of the galaxy to just off the edge of the
southwestern HI disk. Beyond the bright stellar disk, but within the HI disk,
weak H-alpha is detected with an intensity I(H-alpha) = 0.05 (+0.01 / -0.02)
Rayleighs. Since M31 is inclined 77 degrees with respect to the line of sight,
this implies that the ambient intergalactic ionizing flux onto each side of M31
is Phi_0 <= 1.6 x 10^4 photons cm^-2 s^-1. Just beyond the outer boundary of
the HI disk we find no significant detection of H-alpha and place an upper
limit I(H-alpha) <= 0.019 Rayleighs.Comment: To appear in ApJ Letters; 12 pages, 4 figure
WHAM Observations of H-alpha Emission from High Velocity Clouds in the M, A, and C Complexes
The first observations of the recently completed Wisconsin H-Alpha Mapper
(WHAM) facility include a study of emission lines from high velocity clouds in
the M, A, and C complexes, with most of the observations on the M I cloud. We
present results including clear detections of H-alpha emission from all three
complexes with intensities ranging from 0.06 R to 0.20 R. In every observed
direction where there is significant high velocity H I gas seen in the 21 cm
line we have found associated ionized hydrogen emitting the H-alpha line. The
velocities of the H-alpha and 21 cm emission are well correlated in every case
except one, but the intensities are not correlated. There is some evidence that
the ionized gas producing the H-alpha emission envelopes the 21 cm emitting
neutral gas but the H-alpha "halo", if present, is not large. If the H-alpha
emission arises from the photoionization of the H I clouds, then the implied
Lyman continuum flux F_{LC} at the location of the clouds ranges from 1.3 to
4.2 x 10^5 photons cm^{-2} s^{-1}. If, on the other hand, the ionization is due
to a shock arising from the collision of the high-velocity gas with an ambient
medium in the halo, then the density of the pre-shocked gas can be constrained.
We have also detected the [S II] 6716 angstrom line from the M I cloud and have
evidence that the [S II] to H-alpha ratio varies with location on the cloud.Comment: 32 pages, 18 figures, to appear in ApJ (Sept. 10, 1998
Galactic contamination in the QMAP experiment
We quantify the level of foreground contamination in the QMAP Cosmic
Microwave Background (CMB) data with two objectives: (a) measuring the level to
which the QMAP power spectrum measurements need to be corrected for foregrounds
and (b) using this data set to further refine current foreground models. We
cross-correlate the QMAP data with a variety of foreground templates. The 30
GHz Ka-band data is found to be significantly correlated with the Haslam 408
MHz and Reich and Reich 1420 MHz synchrotron maps, but not with the Diffuse
Infrared Background Experiment (DIRBE) 240, 140 and 100 micron maps or the
Wisconsin H-Alpha Mapper (WHAM) survey. The 40 GHz Q-band has no significant
template correlations. We discuss the constraints that this places on
synchrotron, free-free and dust emission. We also reanalyze the
foreground-cleaned Ka-band data and find that the two band power measurements
are lowered by 2.3% and 1.3%, respectively.Comment: 4 ApJL pages, including 4 figs. Color figures and data at
http://www.hep.upenn.edu/~angelica/foreground.html#qmap or from
[email protected]
Westerbork HI observations of high-velocity clouds near M31 and M33
We have undertaken high-resolution follow-up of a sample of high velocity HI
clouds apparently associated with M31. Our sample was chosen from the
population of high-velocity clouds (HVCs) detected out to 50 kpc projected
radius of the Andromeda Galaxy by Thilker et al. (2004) with the Green Bank
Telescope. Nine pointings were observed with the Westerbork Synthesis Radio
Telescope to determine the physical parameters of these objects and to find
clues to their origin. One additional pointing was directed at a similar object
near M33. At 2' resolution we detect 16 individual HVCs around M31 and 1 HVC
near M33 with typical HI masses of a few times 10^5 solar masses and sizes of
the order of 1 kpc. Estimates of the dynamical and virial masses of some of the
HVCs indicate that they are likely gravitationally dominated by additional mass
components such as dark matter or ionised gas. Twelve of the clouds are
concentrated in an area of only 1 by 1 degree at a projected separation of less
than 15 kpc from the disk of M31. This HVC complex has a rather complicated
morphological and kinematical structure and partly overlaps with the giant
stellar stream of M31, suggesting a tidal origin. Another detected feature is
in close proximity, in both position and velocity, with NGC 205, perhaps also
indicative of tidal processes. Other HVCs in our survey are isolated and might
represent primordial, dark-matter dominated clouds.Comment: 18 pages, 16 figures, accepted for publication in Astronomy &
Astrophysic
Quantifying the Performance of Individual Players in a Team Activity
Teamwork is a fundamental aspect of many human activities, from business to art and from sports to science. Recent research suggest that team work is of crucial importance to cutting-edge scientific research, but little is known about how teamwork leads to greater creativity. Indeed, for many team activities, it is not even clear how to assign credit to individual team members. Remarkably, at least in the context of sports, there is usually a broad consensus on who are the top performers and on what qualifies as an outstanding performance.In order to determine how individual features can be quantified, and as a test bed for other team-based human activities, we analyze the performance of players in the European Cup 2008 soccer tournament. We develop a network approach that provides a powerful quantification of the contributions of individual players and of overall team performance.We hypothesize that generalizations of our approach could be useful in other contexts where quantification of the contributions of individual team members is important
A New Spin on Galactic Dust
We present a new puzzle involving Galactic microwave emission and attempt to
resolve it. On one hand, a cross-correlation analysis of the WHAM H-alpha map
with the Tenerife 10 and 15 GHz maps shows that the well-known DIRBE correlated
microwave emission cannot be dominated by free-free emission. On the other
hand, recent high resolution observations in the 8-10 GHz range with the Green
Bank 140 ft telescope by Finkbeiner et al. failed to find the corresponding 8
sigma signal that would be expected in the simplest spinning dust models. So
what physical mechanism is causing this ubiquitous dust-correlated emission? We
argue for a model predicting that spinning dust is the culprit after all, but
that the corresponding small grains are well correlated with the larger grains
seen at 100 micron only on large angular scales. In support of this grain
segregation model, we find the best spinning dust template to involve higher
frequency maps in the range 12-60 micron, where emission from transiently
heated small grains is important. Upcoming CMB experiments such as ground-based
interferometers, MAP and Planck LFI with high resolution at low frequencies
should allow a definitive test of this model.Comment: Minor revisions to match accepted ApJ version. 6 pages, 4 figs. Color
figures and more foreground information at
http://www.hep.upenn.edu/~angelica/foreground.html#spin or from
[email protected]
Some considerations for the communication of results of air pollution health effects tracking
Communicating effectively and efficiently on air quality and its health impacts is an important but difficult and complex task. It requires careful consideration of the audience one wants to reach, the messages one is trying to present, the venue through which the message will be delivered. The audience, context, technique, and content factors may affect how well it is heard and how appropriately it is interpreted. In this short paper, I describe many of these concerns and provide some suggestions for how best to address them. However, since every audience differs in goals, characteristics, and nature, what is most important is implementing an effective communications program. This program should include frequent two-way communication, repeated and on-going evaluation of how well the audience understands the messages, and consideration of how to improve the delivery
Tuning of metal-insulator transition of two-dimensional electrons at parylene/SrTiO interface by electric field
Electrostatic carrier doping using a field-effect-transistor structure is an
intriguing approach to explore electronic phases by critical control of carrier
concentration. We demonstrate the reversible control of the insulator-metal
transition (IMT) in a two dimensional (2D) electron gas at the interface of
insulating SrTiO single crystals. Superconductivity was observed in a
limited number of devices doped far beyond the IMT, which may imply the
presence of 2D metal-superconductor transition. This realization of a
two-dimensional metallic state on the most widely-used perovskite oxide is the
best manifestation of the potential of oxide electronics
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