144 research outputs found
Information visualization for the people
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Comparative Media Studies, 2008.Includes bibliographical references (p. 85-89).The design of information visualization, defined as the interactive, graphical presentation of data, is on the verge of a significant paradigm shift brought on by the continued maturation of the Information Age. Its traditional role as a scientific tool deployed by rigorous data analysts is in the process of expanding to include more mainstream uses and users, reflecting fundamental changes to the role of information and data in our increasingly digital society. However, visualization design theory remains rooted in earlier conceptions of its use, largely ignoring the needs of this new, non-expert audience. Accordingly, this thesis attempts to re-contextualize information visualization as a public-facing practice, and explores ways in which its design can shift from being described as "by experts, for experts" to a new characterization as "for the people."by Michael Danziger.S.M
Systematic Blueshift of Line Profiles in the Type IIn Supernova 2010jl: Evidence for Post-Shock Dust Formation?
Type IIn SNe show spectral evidence for strong interaction between their
blast wave and dense circumstellar material (CSM) around the progenitor star.
SN2010jl was the brightest core-collapse SN in 2010, and it was a Type IIn
explosion with strong CSM interaction. Andrews et al. recently reported
evidence for an IR excess in SN2010jl, indicating either new dust formation or
the heating of CSM dust in an IR echo. Here we report multi-epoch spectra of
SN2010jl that reveal the tell-tale signature of new dust formation:
emission-line profiles becoming systematically more blueshifted as the red side
of the line is blocked by increasing extinction. The effect is seen clearly in
the intermediate-width (400--4000 km/s) component of H beginning
roughly 30d after explosion. Moreover, we present near-IR spectra demonstrating
that the asymmetry in the hydrogen-line profiles is wavelength dependent,
appearing more pronounced at shorter wavelengths. This evidence suggests that
new dust grains had formed quickly in the post-shock shell of SN 2010jl arising
from CSM interaction. Since the observed dust temperature has been attributed
to an IR echo and not to new dust, either (1) IR excess emission at m is not a particularly sensitive tracer of new dust formation in SNe, or
(2) some assumptions about expected dust temperatures might require further
study. Lastly, we discuss one possible mechanism other than dust that might
lead to increasingly blueshifted line profiles in SNeIIn, although the
wavelength dependence of the asymmetry argues against this hypothesis in the
case of SN2010jl.Comment: 6 pages, 4 figures, submitted to A
Proton-pump inhibitor use is associated with low serum magnesium concentrations
Although case reports link proton-pump inhibitor (PPI) use and hypomagnesemia, no large-scale studies have been conducted. Here we examined the serum magnesium concentration and the likelihood of hypomagnesemia ( < 1.6 mg/dl) with a history of PPI or histamine-2 receptor antagonist used to reduce gastric acid, or use of neither among 11,490 consecutive adult admissions to an intensive care unit of a tertiary medical center. Of these, 2632 patients reported PPI use prior to admission, while 657 patients were using a histamine-2 receptor antagon ist. PPI use was associated with 0.012 mg/dl lower adjusted serum magnesium concentration compared to users of no acid-suppressive medications, but this effect was restricted to those patients taking diuretics. Among the 3286 patients concurrently on diuretics, PPI use was associated with a significant increase of hypomagnesemia (odds ratio 1.54) and 0.028 mg/dl lower serum magnesium concentration. Among those not using diuretics, PPI use was not associated with serum magnesium levels. Histamine-2 receptor antagonist use was not significantly associated with magnesium concentration without or with diuretic use. The use of PPI was not associated with serum phosphate concentration regardless of diuretic use. Thus, we verify case reports of the association between PPI use and hypomagnesemia in those concurrently taking diuretics. Hence, serum magnesium concentrations should be followed in susceptible individuals on chronic PPI therapy.National Institute of Biomedical Imaging and Bioengineering (U.S.) (Grant 2R01 EB001659
Feedback in the cores of clusters Abell 3581, 2A 0335+096, and Sersic 159-03
The cores of massive galaxy clusters, where hot gas is cooling rapidly,
appear to undergo cycles of self-regulating energy feedback, in which AGN
outbursts in the central galaxies episodically provide sufficient heating to
offset much of the gas cooling. We use deep integral-field spectroscopy to
study the optical line emission from the extended nebulae of three nearby
brightest cluster galaxies and investigate how they are related to the
processes of heating and cooling in the cluster cores. Two of these systems,
Abell 3581 and Sersic 159-03, appear to be experiencing phases of feedback that
are dominated by the activity and output of a central AGN. Abell 3581, shows
evidence for significant interaction between the radio outflows and the optical
nebula, in addition to accretion flows into the nucleus of the galaxy. X-ray
and radio data show that Sersic 159-03 is dominated by the feedback of energy
from the central AGN, but the kinematics of the optical nebula are consistent
with infall or outflow of material along its bright filaments. The third
system, 2A 0335+096, is dominated by mass accretion and cooling, and so we
suggest that it is in an accumulation phase of the feedback cycle. The outer
nebula forms a disk-like structure, ~14 kpc in radius, that rotates about the
central galaxy with a velocity amplitude of ~200 km/s. Overall, our data are
consistent with ongoing AGN-driven feedback cycles occurring in these systems.Comment: Preprint: 37 pages with 11 figures and 4 tables, accepted for
publication in Ap
BVRI Light Curves for 29 Type Ia Supernovae
BVRI light curves are presented for 27 Type Ia supernovae discovered during
the course of the Calan/Tololo Survey and for two other SNe Ia observed during
the same period. Estimates of the maximum light magnitudes in the B, V, and I
bands and the initial decline rate parameter m15(B) are also given.Comment: 17 pages, figures and tables are not included (contact first author
if needed), to appear in the Astronomical Journa
An X-ray Spectral Survey of Radio-Loud AGN With ASCA
We present a uniform and systematic analysis of the 0.6-10 keV X-ray spectra
of radio-loud active galactic nuclei (AGN) observed by ASCA. The sample 10
BLRGs, 5 QSRs, 9 NLRGs, and 10 RGs. At soft X-rays, about half of the NLRGs and
all of the RGs exhibit a thermal plasma component, with a bimodal distribution
of temperatures and luminosities, suggesting an origin either in a surrounding
cluster or loose group or in a hot corona. At energies above 2 keV, a hard
power-law component is detected in 90% of cases. The power-law photon indices
and luminosities in BLRGs, QSRs, and NLRGs are similar, consistent with
orientation-based unification schemes. Significant excess cold absorption is
detected in most NLRGs, but also in some BLRGS and QSRs, which was somewhat
unexpected. In contrast to Seyfert galaxies, only one object showss the
signature of a warm absorber. The nuclear X-ray luminosity is correlated with
the luminosity of the [O III] emission line, the FIR emission at 12 microns,
and the lobe radio power at 5 GHz. The Fe K line is detected in 50% of BLRGs,
one QSR, and a handful of NLRGs. This sample also includes 6 Weak Line Radio
Galaxies (WLRGs). Their spectra WLRGs can be generally decomposed into a soft
thermal component with hard absrorbed power-law component, which is
significantly flatter than any other radio-loud AGNs. Their intrinsic
luminosities are two orders of magnitude lower than in other sources of the
sample. An interesting possibility is that WLRGs represent an extreme
population of radio galaxies in which the central black hole is accreting at a
rate well below the Eddington rate.Comment: To appear in the Astrophysical Journal. 72 pages, including many
tables and figures. Fig 1 is separate, in TIFF format. Postscript version of
fig 1 and postscript version of entire preprint can be obtained from
http://www.astro.psu.edu/users/mce/preprint_index.htm
Authentic Leadership: A Historical Perspective
The purpose of this paper is to interpret the historical meanings conveyed by Barnard's classic works and use them for theorizing about authenticity of leaders in executive roles. Our analysis employs an interpretative logic for meanings of historical ideas proposed by Bevir. As an outcome of this analysis, we identify the conditions that contribute to the failure, crisis, tragedy, and/or success of leader authenticity. In addition, we discuss practical and research implications of the proposed framework.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Six Years of Chandra Observations of Supernova Remnants
We present a review of the first six years of Chandra X-ray Observatory
observations of supernova remnants. From the official "first-light" observation
of Cassiopeia A that revealed for the first time the compact remnant of the
explosion, to the recent million-second spectrally-resolved observation that
revealed new details of the stellar composition and dynamics of the original
explosion, Chandra observations have provided new insights into the supernova
phenomenon. We present an admittedly biased overview of six years of these
observations, highlighting new discoveries made possible by Chandra's unique
capabilities.Comment: 82 pages, 28 figures, for the book Astrophysics Update
Ensemble-Based Computational Approach Discriminates Functional Activity of p53 Cancer and Rescue Mutants
The tumor suppressor protein p53 can lose its function upon single-point missense mutations in the core DNA-binding domain (“cancer mutants”). Activity can be restored by second-site suppressor mutations (“rescue mutants”). This paper relates the functional activity of p53 cancer and rescue mutants to their overall molecular dynamics (MD), without focusing on local structural details. A novel global measure of protein flexibility for the p53 core DNA-binding domain, the number of clusters at a certain RMSD cutoff, was computed by clustering over 0.7 µs of explicitly solvated all-atom MD simulations. For wild-type p53 and a sample of p53 cancer or rescue mutants, the number of clusters was a good predictor of in vivo p53 functional activity in cell-based assays. This number-of-clusters (NOC) metric was strongly correlated (r2 = 0.77) with reported values of experimentally measured ΔΔG protein thermodynamic stability. Interpreting the number of clusters as a measure of protein flexibility: (i) p53 cancer mutants were more flexible than wild-type protein, (ii) second-site rescue mutations decreased the flexibility of cancer mutants, and (iii) negative controls of non-rescue second-site mutants did not. This new method reflects the overall stability of the p53 core domain and can discriminate which second-site mutations restore activity to p53 cancer mutants
Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope
We present ultraviolet (UV) spectroscopy and photometry of four Type Ia
supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism
of the Advanced Camera for Surveys on the Hubble Space Telescope. This dataset
provides unique spectral time series down to 2000 Angstrom. Significant
diversity is seen in the near maximum-light spectra (~ 2000--3500 Angstrom) for
this small sample. The corresponding photometric data, together with archival
data from Swift Ultraviolet/Optical Telescope observations, provide further
evidence of increased dispersion in the UV emission with respect to the
optical. The peak luminosities measured in uvw1/F250W are found to correlate
with the B-band light-curve shape parameter dm15(B), but with much larger
scatter relative to the correlation in the broad-band B band (e.g., ~0.4 mag
versus ~0.2 mag for those with 0.8 < dm15 < 1.7 mag). SN 2004dt is found as an
outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia
such as SN 2005cf by ~0.9 mag and ~2.0 mag in the uvw1/F250W and uvm2/F220W
filters, respectively. We show that different progenitor metallicity or
line-expansion velocities alone cannot explain such a large discrepancy.
Viewing-angle effects, such as due to an asymmetric explosion, may have a
significant influence on the flux emitted in the UV region. Detailed modeling
is needed to disentangle and quantify the above effects.Comment: 17 pages, 13 figures, accepted by Ap
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