3,711 research outputs found
Curbing the Market for Cyber Weapons
President Obama recently warned that foreign governments, criminal syndicates and lone individuals are probing our financial, energy and public safety systems every day and that in a future conflict, an adversary unable to match our military supremacy on the battlefield might seek to exploit our computer vulnerabilities here at home. \u27 Until recently, the technical challenges of identifying and exploiting U.S. computer vulnerabilities impeded all but the most powerful of nations from acquiring such capabilities. These impediments have vanished. Now, criminals, terrorists, and rogue nations can simply buy what they need in a booming online market for the most dangerous exploits of all: weaponized 0day exploits
PG 1700+518 Revisited: Adaptive Optics Imaging and a Revised Starburst Age for the Companion
We present the results of adaptive-optics imaging of the z=0.2923 QSO PG
1700+518 in the J and H bands. The extension to the north of the QSO is clearly
seen to be a discrete companion with a well-defined tidal tail, rather than a
feature associated with the host galaxy of PG 1700+518 itself. On the other
hand, an extension to the southwest of the QSO (seen best in deeper, but
lower-resolution, optical images) does likely comprise tidal material from the
host galaxy. The SED derived from images in J, H, and two non-standard optical
bands indicates the presence of dust intermixed with the stellar component. We
use our previously reported Keck spectrum of the companion, the SED found from
the imaging data, and updated spectral-synthesis models to constrain the
stellar populations in the companion and to redetermine the age of the
starburst. While our best-fit age of 0.085 Gyr is nearly the same as our
earlier determination, the fit of the new models is considerably better. This
age is found to be remarkably robust with respect to different assumptions
about the nature of the older stellar component and the effects of dust.Comment: 11 pages; includes two eps figures. Latex (AASTEX). Two additional
figures in gif format. Postscript version including all figs. (424 kb) can be
obtained from http://www.ifa.hawaii.edu/~canaguby/preprints.html To appear in
ApJ. Letter
Levelling Up for health in towns? Development of a new deprivation index: the 'Stronger Towns Index' and its association with self-rated health and migration in England, between 2001 and 2011
Aim: To develop the âStronger Towns Index': a deprivation index that took into account characteristics of areas encompassing towns that may be eligible for redevelopment funding and explore how this index was associated with self-rated health and migration within England between 2001 and 2011. / Subject and methods: All members of the ONS Longitudinal Study in England aged 16 and over in 2001 whose records included a self-rated health response and a valid local authority code. Local authorities in England were ranked using a composite index developed using the five metrics set out in the Stronger Towns Funding: productivity, income, skills, deprivation measures, and the proportion of people living in towns. The index was split into deciles, and logistic regression carried out on the association between decile and self-rated health in 2001 in the main sample (n = 407,878) and decile change and self-rated health in 2011 in a subsample also present in 2011, with migration information (n = 299,008). / Results: There were areas in the lowest deciles of Town Strength who did not receive funding. After multiple adjustment, LS members living in areas with higher deciles were significantly more likely (7% to 38%) to report good health than those in the lowest decile in 2001. Remaining in the same decile between 2001 and 2011 was associated with 7% lower odds of good self-rated health in 2011. / Conclusion: It is important to consider health in towns when allocating funding. Areas in the Midlands may have missed out on funding which might help mitigate poor health
Extremely Red Objects in Two Quasar Fields at z ~ 1.5
We present an investigation of the properties and environments of bright
extremely red objects (EROs) found in the fields of the quasars TXS 0145+386
and 4C 15.55, both at z ~ 1.4. There is marginal evidence from Chandra ACIS
imaging for hot cluster gas with a luminosity of a few 10^44 ergs/s in the
field of 4C 15.55. The TXS 0145+386 field has an upper limit at a similar
value, but it also clearly shows an overdensity of faint galaxies. None of the
EROs are detected as X-ray sources. For two of the EROs that have
spectral-energy distributions and rest-frame near-UV spectra that show that
they are strongly dominated by old stellar populations, we determine
radial-surface-brightness profiles from adaptive-optics images. Both of these
galaxies are best fit by profiles close to exponentials, plus a compact nucleus
comprising ~30% of the total light in one case and 8% in the other. Neither is
well fit by an r^1/4-law profile. This apparent evidence for the formation of
massive ~2 X 10^11 disks of old stars in the early universe indicates that at
least some galaxies formed essentially monolithically, with high star-formation
rates sustained over a few 10^8 years, and without the aid of major mergers.Comment: 25 pages, 13 figures, accepted to Ap
Our New National Security Strategy: America Promises to Come Back and Reconstituting America\u27s Defense: The New U.S. National Security Strategy
The Nature of Optical Features in the Inner Region of the 3C48 Host Galaxy
The well-known quasar 3C48 is the most powerful compact steep-spectrum
radio-loud QSO at low redshifts. It also has two unusual optical features
within the radius of the radio jet (~1"): (1) an anomalous, high-velocity
narrow-line component, having several times as much flux as does the
narrow-line component coinciding with the broad-line redshift; and (2) a bright
continuum peak (3C48A) ~1" northeast of the quasar. Both of these optical
features have been conjectured to be related to the radio jet. Here we explore
these suggestions. We have obtained Gemini North GMOS integral-field-unit (IFU)
spectroscopy of the central region around 3C48. We use the unique features of
the IFU data to remove unresolved emission at the position of the quasar. The
resolved emission at the wavelength of the high-velocity component is peaked
<~0.25" north of the quasar, at virtually the same position angle as the base
of the radio jet. These observations appear to confirm that this high-velocity
gas is connected with the radio jet. However, most of the emission comes from a
region where the jet is still well collimated, rather than from the regions
where the radio maps indicate strong interaction with an external medium. We
also present the results of HST STIS spectroscopy of 3C48A. We show that 3C48A
is dominated by stars with a luminosity-weighted age of ~1.4 X 10^8 years,
substantially older than any reasonable estimate for the age of the radio
source. Our IFU data indicate a similar age. Thus, 3C48A almost certainly
cannot be attributed to jet-induced star formation. The host galaxy of 3C48 is
clearly the result of a merger, and 3C48A seems much more likely to be the
distorted nucleus of the merging partner, in which star formation was induced
during the previous close passage.Comment: 10 pages, accepted by The Astrophysical Journa
Paul N. Stockton: a biography
Paul N. Stockton was nominated by President
Barack Obama to be the Assistant Secretary of
Defense for Homeland Defense and Americasâ
Security Affairs on April 28, 2009, and confirmed
by the Senate on May 18, 2009. In this position, he
is responsible for the supervision of homeland
defense activities, defense support of civil
authorities, and Western Hemisphere security
affairs for the Department of Defense
3C 48: Stellar Populations and the Kinematics of Stars and Gas in the Host Galaxy
We present deep Keck LRIS spectroscopy of the host galaxy of 3C 48. Our
observations at various slit positions sample the different luminous components
near the quasar, including the apparent tidal tail to the NW and several strong
emission line regions.
By fitting Bruzual & Charlot (1996) population synthesis models to our
spectra, we obtain ages for the most recent major episodes of star formation in
various parts of the host galaxy covered by our slits. There is vigorous
current star formation in regions just NE and SE of the quasar and
post-starburst regions with ages up to ~10^8 years in other parts of the host
galaxy, but most of the NW tidal tail shows no sign of significant recent star
formation. We use these model fits, together with the kinematics of the stars
and gas, to outline a plausible evolutionary history for the host galaxy, its
recent starburst activity, the triggering of the quasar, and the interaction of
the radio jet with the ambient gas.
There is strong evidence that the 3C 48 host is an ongoing merger, and that
it is probably near the peak of its starburst activity. Nevertheless, the
quasar itself seems to suffer little extinction, perhaps because we are viewing
it along a particularly favorable line-of-sight.Comment: 27 pages plus 11 figures (7 postscript, 4 gif). Postscript version
including figures (1840 kb) available at
http://www.ifa.hawaii.edu/~canaguby/preprints.html . Accepted for publication
in Ap
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