832 research outputs found
Learning to communicate about shared procedural abstractions
Many real-world tasks require agents to coordinate their behavior to achieve
shared goals. Successful collaboration requires not only adopting the same
communicative conventions, but also grounding these conventions in the same
task-appropriate conceptual abstractions. We investigate how humans use natural
language to collaboratively solve physical assembly problems more effectively
over time. Human participants were paired up in an online environment to
reconstruct scenes containing two block towers. One participant could see the
target towers, and sent assembly instructions for the other participant to
reconstruct. Participants provided increasingly concise instructions across
repeated attempts on each pair of towers, using higher-level referring
expressions that captured each scene's hierarchical structure. To explain these
findings, we extend recent probabilistic models of ad-hoc convention formation
with an explicit perceptual learning mechanism. These results shed light on the
inductive biases that enable intelligent agents to coordinate upon shared
procedural abstractions
The modelled climatic response to the 18.6-year lunar nodal cycle and its role in decadal temperature trends
The 18.6-year lunar nodal cycle arises from variations in the angle of the Moon’s orbital plane. Previous work has linked the nodal cycle to climate but has been limited, either by the length of observations analysed, or geographical regions considered in model simulations of the pre-industrial period. Here we examine the global effect of the lunar nodal cycle in multi-centennial climate model simulations of the pre-industrial period. We find cyclic signals in global and regional surface air temperature having amplitudes of O (0.1 K), ocean heat uptake and ocean heat content. The timing of anomalies of global surface air temperature and heat uptake are consistent with the so-called slowdown in global warming in the first decade of the 21st century, also displaying warmer than average Arctic surface temperatures at the same time. The lunar nodal cycle causes variations in mean sea level pressure exceeding 0.5 hPa in the Nordic seas region, thus affecting the North Atlantic Oscillation Index during boreal winter. Our results suggest that the contribution of the lunar nodal cycle to global temperature should be negative in the mid-2020s before becoming positive again in the early-2030s, reducing the uncertainty in time at which projected global temperature reaches 1.5C above pre-industrial levels
Binary Quasars in the Sloan Digital Sky Survey: Evidence for Excess Clustering on Small Scales
We present a sample of 218 new quasar pairs with proper transverse
separations R_prop < 1 Mpc/h over the redshift range 0.5 < z < 3.0, discovered
from an extensive follow up campaign to find companions around the Sloan
Digital Sky Survey and 2dF Quasar Redshift Survey quasars. This sample includes
26 new binary quasars with separations R_prop < 50 kpc/h (theta < 10
arcseconds), more than doubling the number of such systems known. We define a
statistical sample of binaries selected with homogeneous criteria and compute
its selection function, taking into account sources of incompleteness. The
first measurement of the quasar correlation function on scales 10 kpc/h <
R_prop < 400 kpc/h is presented. For R_prop < 40 kpc/h, we detect an order of
magnitude excess clustering over the expectation from the large scale R_prop >
3 Mpc/h quasar correlation function, extrapolated down as a power law to the
separations probed by our binaries. The excess grows to ~ 30 at R_prop ~ 10
kpc/h, and provides compelling evidence that the quasar autocorrelation
function gets progressively steeper on sub-Mpc scales. This small scale excess
can likely be attributed to dissipative interaction events which trigger quasar
activity in rich environments. Recent small scale measurements of galaxy
clustering and quasar-galaxy clustering are reviewed and discussed in relation
to our measurement of small scale quasar clustering.Comment: 25 pages, 12 figures, 9 tables. Submitted to the Astronomical Journa
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The inositol-3-phosphate synthase biosynthetic enzyme has distinct catalytic and metabolic roles
Inositol levels, maintained by the biosynthetic enzyme inositol-3-phosphate synthase (Ino1), are altered in a range of disorders including bipolar disorder and Alzheimer's disease. To date, most inositol studies have focused on the molecular and cellular effects of inositol depletion without considering Ino1 levels. Here we employ a simple eukaryote, Dictyostelium, to demonstrate distinct effects of loss of Ino1 and inositol depletion. We show that loss of Ino1 results in inositol auxotrophy that can only be partially rescued by exogenous inositol. Removal of inositol supplementation from the ino1- mutant results in a rapid 56% reduction in inositol levels, triggering the induction of autophagy, reduced cytokinesis and substrate adhesion. Inositol depletion also caused a dramatic generalised decrease in phosphoinositide levels that was rescued by inositol supplementation. However, loss of Ino1 triggered broad metabolic changes consistent with the induction of a catabolic state that was not rescued by inositol supplementation. These data suggest a metabolic role for Ino1 independent of inositol biosynthesis. To characterise this role, an Ino1 binding partner containing SEL1L1 domains (Q54IX5) was identified with homology to mammalian macromolecular complex adaptor proteins. Our findings therefore identify a new role for Ino1, independent of inositol biosynthesis, with broad effects on cell metabolism
The Ensemble Photometric Variability of ~25000 Quasars in the Sloan Digital Sky Survey
Using a sample of over 25000 spectroscopically confirmed quasars from the
Sloan Digital Sky Survey, we show how quasar variability in the rest frame
optical/UV regime depends upon rest frame time lag, luminosity, rest
wavelength, redshift, the presence of radio and X-ray emission, and the
presence of broad absorption line systems. The time dependence of variability
(the structure function) is well-fit by a single power law on timescales from
days to years. There is an anti-correlation of variability amplitude with rest
wavelength, and quasars are systematically bluer when brighter at all
redshifts. There is a strong anti-correlation of variability with quasar
luminosity. There is also a significant positive correlation of variability
amplitude with redshift, indicating evolution of the quasar population or the
variability mechanism. We parameterize all of these relationships. Quasars with
RASS X-ray detections are significantly more variable (at optical/UV
wavelengths) than those without, and radio loud quasars are marginally more
variable than their radio weak counterparts. We find no significant difference
in the variability of quasars with and without broad absorption line troughs.
Models involving multiple discrete events or gravitational microlensing are
unlikely by themselves to account for the data. So-called accretion disk
instability models are promising, but more quantitative predictions are needed.Comment: 41 pages, 21 figures, AASTeX, Accepted for publication in Ap
The blameworthiness of health and safety rule violations
Man-made disasters usually lead to the tightening of safety regulations, because rule breaking is seen as a major cause of them. This reaction is based on the presumptions that the safety rules are good and that the rule-breakers are wrong. The reasons the personnel of a coke factory gave for breaking rules raise doubt about the tenability of these presumptions. It is unlikely that this result would have been achieved on the basis of a disaster evaluation or High-Reliability Theory. In both approaches, knowledge of the consequences of human conduct hinders an unprejudiced judgement about the blameworthiness of rule breaking
Communicating about self and others within an online support group for women with breast cancer and subsequent outcomes
Abstract Research suggests communicating too much about one's self within an online support group may amplify breast cancer patients' focus on their own problems and exacerbate negative emotions while focusing on others may have the opposite effects. This study explored how pronoun usage within an online support group was associated with subsequent mental health outcomes. There were 286 patients recruited into the study who filled out the pre-test and 231 completed post-tests four months later with survey measures including breast cancer-related concerns and negative emotions. Messages were analyzed using a program counting first person and relational pronouns. A positive relationship was found between use of first person pronouns and negative emotions
A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
We provide a quantitative description and statistical interpretation of the
optical continuum variability of quasars. The Sloan Digital Sky Survey (SDSS)
has obtained repeated imaging in five UV-to-IR photometric bands for 33,881
spectroscopically confirmed quasars. About 10,000 quasars have an average of 60
observations in each band obtained over a decade along Stripe 82 (S82), whereas
the remaining ~25,000 have 2-3 observations due to scan overlaps. The observed
time lags span the range from a day to almost 10 years, and constrain quasar
variability at rest-frame time lags of up to 4 years, and at rest-frame
wavelengths from 1000A to 6000A. We publicly release a user-friendly catalog of
quasars from the SDSS Data Release 7 that have been observed at least twice in
SDSS or once in both SDSS and the Palomar Observatory Sky Survey, and we use it
to analyze the ensemble properties of quasar variability. Based on a damped
random walk (DRW) model defined by a characteristic time scale and an
asymptotic variability amplitude that scale with the luminosity, black hole
mass, and rest wavelength for individual quasars calibrated in S82, we can
fully explain the ensemble variability statistics of the non-S82 quasars such
as the exponential distribution of large magnitude changes. All available data
are consistent with the DRW model as a viable description of the optical
continuum variability of quasars on time scales of ~5-2000 days in the rest
frame. We use these models to predict the incidence of quasar contamination in
transient surveys such as those from PTF and LSST.Comment: 33 pages, 19 figures, replaced with accepted version. Catalog is
available at http://www.astro.washington.edu/users/ivezic/macleod/qso_dr7
HSD3B1 genotype identifies glucocorticoid responsiveness in severe asthma
Asthma resistance to glucocorticoid treatment is a major health problem with unclear etiology. Glucocorticoids inhibit adrenal androgen production. However, androgens have potential benefits in asthma. HSD3B1 encodes for 3β-hydroxysteroid dehydrogenase-1 (3β-HSD1), which catalyzes peripheral conversion from adrenal dehydroepiandrosterone (DHEA) to potent androgens and has a germline missense-encoding polymorphism. The adrenal restrictive HSD3B1(1245A) allele limits conversion, whereas the adrenal permissive HSD3B1(1245C) allele increases DHEA metabolism to potent androgens. In the Severe Asthma Research Program (SARP) III cohort, we determined the association between DHEA-sulfate and percentage predicted forced expiratory volume in 1 s (FEV1PP). HSD3B1(1245) genotypes were assessed, and association between adrenal restrictive and adrenal permissive alleles and FEV1PP in patients with (GC) and without (noGC) daily oral glucocorticoid treatment was determined (n = 318). Validation was performed in a second cohort (SARP I&II; n = 184). DHEA-sulfate is associated with FEV1PP and is suppressed with GC treatment. GC patients homozygous for the adrenal restrictive genotype have lower FEV1PP compared with noGC patients (54.3% vs. 75.1%; P < 0.001). In patients with the homozygous adrenal permissive genotype, there was no FEV1PP difference in GC vs. noGC patients (73.4% vs. 78.9%; P = 0.39). Results were independently confirmed: FEV1PP for homozygous adrenal restrictive genotype in GC vs. noGC is 49.8 vs. 63.4 (P < 0.001), and for homozygous adrenal permissive genotype, it is 66.7 vs. 67.7 (P = 0.92). The adrenal restrictive HSD3B1(1245) genotype is associated with GC resistance. This effect appears to be driven by GC suppression of 3β-HSD1 substrate. Our results suggest opportunities for prediction of GC resistance and pharmacologic intervention
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