1,955 research outputs found
Circumventing Concept Erasure Methods For Text-to-Image Generative Models
Text-to-image generative models can produce photo-realistic images for an
extremely broad range of concepts, and their usage has proliferated widely
among the general public. On the flip side, these models have numerous
drawbacks, including their potential to generate images featuring sexually
explicit content, mirror artistic styles without permission, or even
hallucinate (or deepfake) the likenesses of celebrities. Consequently, various
methods have been proposed in order to "erase" sensitive concepts from
text-to-image models. In this work, we examine five recently proposed concept
erasure methods, and show that targeted concepts are not fully excised from any
of these methods. Specifically, we leverage the existence of special learned
word embeddings that can retrieve "erased" concepts from the sanitized models
with no alterations to their weights. Our results highlight the brittleness of
post hoc concept erasure methods, and call into question their use in the
algorithmic toolkit for AI safety
Neurobiology of Disease Hippocampal Hyperactivation Associated with Cortical Thinning in Alzheimer's Disease Signature Regions in Non-Demented Elderly Adults
Alzheimer's disease (AD) is associated with functional and structural alterations in a distributed network of brain regions supporting memory and other cognitive domains. Functional abnormalities are present in mild cognitive impairment (MCI) with evidence of early hyperactivity in medial temporal lobe regions, followed by failure of hippocampal activation as dementia develops. Atrophy in a consistent set of cortical regions, the "cortical signature of AD," has been reported at the stage of dementia, MCI, and even in clinically normal (CN) older individuals predicted to develop AD. Despite multiple lines of evidence for each of these findings, the relationship between this structural marker of AD-related neurodegeneration and this functional marker of the integrity of the episodic memory system has not yet been elucidated. We investigated this relationship in 34 nondemented older humans (CN, N ϭ 18; MCI, N ϭ 16). Consistent with previous studies, we found evidence of hippocampal hyperactivation in MCI compared with CN. Additionally, within this MCI group, increased hippocampal activation correlated with cortical thinning in AD-signature regions. Even within the CN group, increased hippocampal activity was negatively correlated with cortical thinning in a subset of regions, including the superior parietal lobule (r ϭ Ϫ0.66; p Ͻ 0.01). These findings, across a continuum of nondemented and mildly impaired older adults, support the hypothesis that paradoxically increased hippocampal activity may be an early indicator of AD-related neurodegeneration in a distributed network
The X-ray properties of typical high-redshift radio-loud quasars
We report spectral, imaging, and variability results from four new XMM-Newton
observations and two new Chandra observations of high-redshift (z > 4)
radio-loud quasars (RLQs). Our targets span lower, and more representative,
values of radio loudness than those of past samples of high-redshift RLQs
studied in the X-ray regime. Our spectral analyses show power-law X-ray
continua with a mean photon index, \Gamma =1.74 +/- 0.11, that is consistent
with measurements of lower redshift RLQs. These continua are likely dominated
by jet-linked X-ray emission, and they follow the expected anti-correlation
between photon index and radio loudness. We find no evidence of iron K\alpha ~
emission lines or Compton-reflection continua. Our data also constrain
intrinsic X-ray absorption in these RLQs. We find evidence for significant
absorption (N_H ~ 10^22 cm^-2) in one RLQ of our sample (SDSS J0011+1446); the
incidence of X-ray absorption in our sample appears plausibly consistent with
that for high-redshift RLQs that have higher values of radio loudness. In the
Chandra observation of PMN J221-2719 we detect apparent extended (~ 14 kpc)
X-ray emission that is most likely due to a jet; the X-ray luminosity of this
putative jet is ~2% that of the core. The analysis of a 4.9 GHz VLA image of
PMN J221-2719 reveals a structure that matches the X-ray extension found in
this source. We also find evidence for long-term (450-460 days) X-ray
variability by 80-100% in two of our targets.Comment: Paper accepted for publication in the Astrophysical Journa
The High-Metallicity Explosion Environment of the Relativistic Supernova 2009bb
We investigate the environment of the nearby (d ~ 40Mpc) broad-lined Type Ic
supernova SN 2009bb. This event was observed to produce a relativistic outflow
likely powered by a central accreting compact object. While such a phenomenon
was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB
was detected in association with SN 2009bb. Using an optical spectrum of the SN
2009bb explosion site, we determine a variety of ISM properties for the host
environment, including metallicity, young stellar population age, and star
formation rate. We compare the SN explosion site properties to observations of
LGRB and broad-lined SN Ic host environments on optical emission line ratio
diagnostic diagrams. Based on these analyses, we find that the SN 2009bb
explosion site has a very high metallicity of ~2x solar, in agreement with
other broad-lined SN Ic host environments and at odds with the low-redshift
LGRB host environments and recently proposed maximum metallicity limits for
relativistic explosions. We consider the implications of these findings and the
impact that SN 2009bb's unusual explosive properties and environment have on
our understanding of the key physical ingredient that enables some SNe to
produce a relativistic outflow.Comment: 7 pages, 4 figures, 1 table; accepted for publication in ApJ Letters
(replaced to include missing figure
The Sloan Digital Sky Survey Reverberation Mapping Project: Rapid CIV Broad Absorption Line Variability
We report the discovery of rapid variations of a high-velocity CIV broad
absorption line trough in the quasar SDSS J141007.74+541203.3. This object was
intensively observed in 2014 as a part of the Sloan Digital Sky Survey
Reverberation Mapping Project, during which 32 epochs of spectroscopy were
obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We
observe significant (>4sigma) variability in the equivalent width of the broad
(~4000 km/s wide) CIV trough on rest-frame timescales as short as 1.20 days
(~29 hours), the shortest broad absorption line variability timescale yet
reported. The equivalent width varied by ~10% on these short timescales, and by
about a factor of two over the duration of the campaign. We evaluate several
potential causes of the variability, concluding that the most likely cause is a
rapid response to changes in the incident ionizing continuum. If the outflow is
at a radius where the recombination rate is higher than the ionization rate,
the timescale of variability places a lower limit on the density of the
absorbing gas of n_e > 3.9 x 10^5 cm^-3. The broad absorption line variability
characteristics of this quasar are consistent with those observed in previous
studies of quasars, indicating that such short-term variability may in fact be
common and thus can be used to learn about outflow characteristics and
contributions to quasar/host-galaxy feedback scenarios.Comment: 15 pages, 14 figures. Accepted for publication in the Astrophysical
Journa
Cosmological distance indicators
We review three distance measurement techniques beyond the local universe:
(1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and
(3) HI intensity mapping. We describe the principles and theory behind each
method, the ingredients needed for measuring such distances, the current
observational results, and future prospects. Time delays from strongly lensed
quasars currently provide constraints on with < 4% uncertainty, and with
1% within reach from ongoing surveys and efforts. Recent exciting discoveries
of strongly lensed supernovae hold great promise for time-delay cosmography.
BAO features have been detected in redshift surveys up to z <~ 0.8 with
galaxies and z ~ 2 with Ly- forest, providing precise distance
measurements and with < 2% uncertainty in flat CDM. Future BAO
surveys will probe the distance scale with percent-level precision. HI
intensity mapping has great potential to map BAO distances at z ~ 0.8 and
beyond with precisions of a few percent. The next years ahead will be exciting
as various cosmological probes reach 1% uncertainty in determining , to
assess the current tension in measurements that could indicate new
physics.Comment: Review article accepted for publication in Space Science Reviews
(Springer), 45 pages, 10 figures. Chapter of a special collection resulting
from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in
the Space Ag
Exploring concepts of health with male prisoners in three category-C English prisons
Lay understandings of health and illness have a well established track record and a plethora of research now exists which has examined these issues. However, there is a dearth of research which has examined the perspectives of those who are imprisoned. This paper attempts to address this research gap. The paper is timely given that calls have been made to examine lay perspectives in different geographical locations and a need to re-examine health promotion approaches in prison settings. Qualitative data from thirty-six male sentenced prisoners from three prisons in England were collected. The data was analysed in accordance with Attride-Stirling's (2001) thematic network approach. Although the men's perceptions of health were broadly similar to the general population, some interesting findings emerged which were directly related to prison life and its associated structures. These included access to the outdoors and time out of their prison cell, as well as maintaining relationships with family members through visits. The paper proposes that prisoners' lay views should be given higher priority given that prison health has traditionally been associated with medical treatment and the bio-medical paradigm more generally. It also suggests that in order to fulfil the World Health Organization's (WHO) vision of viewing prisons as health promoting settings, lay views should be recognised to shape future health promotion policy and practice
Notes on age determination, size and age structure, longevity, and growth of co-occurring macrourid fishes
ACKNOWLEDGEMENTS We are grateful to crew and colleagues who sampled and processed macrourids on the MARECO and ECOMAR cruise, to Ms Hege Ø Hansen for assistance in the otolith laboratory, and to home institutions and the Alfred P Sloan Foundation for financial support. An early version of the results was submitted in partial fulfilment of the requirements for the MSc degree of R.H. Fundings: Data for this paper were collected on cruises funded by Norway and the United Kingdom (Natural Environment Research Council). In addition to institutional funding, the work benefitted from a grant to the ecosystems of the mid-atlantic ridge (MAR-ECO) Programme from the Alfred P. Sloan Foundation, New York, USA.Peer reviewedPublisher PD
Phase I trial of vorinostat and doxorubicin in solid tumours: histone deacetylase 2 expression as a predictive marker
BackgroundHistone deacetylase inhibitors (HDACi) can sensitise cancer cells to topoisomerase inhibitors by increasing their access and binding to DNA.MethodsThis phase I trial was designed to determine the toxicity profile, tolerability, and recommended phase II dose of escalating doses of the HDACi vorinostat, with weekly doxorubicin.ResultsIn total, 32 patients were treated; vorinostat was dosed at 400, 600, 800, or 1000 mg day(-1) on days 1-3, followed by doxorubicin (20 mg m(-2)) on day 3 for 3 of 4 weeks. Maximal tolerated dose was determined to be 800 mg day(-1) of vorinostat. Dose-limiting toxicities were grade 3 nausea/vomiting (two out of six) and fatigue (one out of six) at 1000 mg day(-1). Non-dose-limiting grade 3/4 toxicities included haematological toxicity and venous thromboembolism. Antitumor activity in 24 evaluable patients included two partial responses (breast and prostate cancer). Two patients with melanoma had stable disease for > or =8 months. Histone hyperacetylation changes in peripheral blood mononuclear and tumour cells were comparable. Histone hyperacetylation seemed to correlate with pre-treatment HDAC2 expression.ConclusionThese findings suggest that vorinostat can be combined with weekly doxorubicin in this schedule at a dose of 800 mg day(-1). The HDAC2 expression may be a marker predictive of HDAC inhibition. Antitumor activity of this regimen in breast cancer, prostate cancer, and melanoma seems interesting
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