2,606 research outputs found
Equivariant Transduction through Invariant Alignment
The ability to generalize compositionally is key to understanding the
potentially infinite number of sentences that can be constructed in a human
language from only a finite number of words. Investigating whether NLP models
possess this ability has been a topic of interest: SCAN (Lake and Baroni, 2018)
is one task specifically proposed to test for this property. Previous work has
achieved impressive empirical results using a group-equivariant neural network
that naturally encodes a useful inductive bias for SCAN (Gordon et al., 2020).
Inspired by this, we introduce a novel group-equivariant architecture that
incorporates a group-invariant hard alignment mechanism. We find that our
network's structure allows it to develop stronger equivariance properties than
existing group-equivariant approaches. We additionally find that it outperforms
previous group-equivariant networks empirically on the SCAN task. Our results
suggest that integrating group-equivariance into a variety of neural
architectures is a potentially fruitful avenue of research, and demonstrate the
value of careful analysis of the theoretical properties of such architectures.Comment: Accepted at COLING 202
A Test of Pre-Main-Sequence Lithium Depletion Models
Despite the extensive study of lithium depletion during pre-main-sequence
contraction, studies of individual stars show discrepancies between ages
determined from the HR diagram and ages determined from lithium depletion (Song
et al. 2002, White & Hillenbrand 2005) indicating open questions in the
pre-main-sequence evolutionary models. To further test these models, we present
high resolution spectra for members of the Beta Pictoris Moving Group (BPMG),
which is young and nearby. We measure equivalent widths of the 6707.8 Angstrom
Li I line in these stars and use them to determine lithium abundances. We
combine the lithium abundance with the predictions of pre-main-sequence
evolutionary models in order to calculate a lithium depletion age for each
star. We compare this age to the age predicted by the HR diagram of the same
model. We find that the evolutionary models under-predict the amount of lithium
depletion for the BPMG given its nominal HR diagram age of ~12 Myr (Zuckerman
et al. 2001), particularly for the mid-M stars, which have no observable Li I
line. This results in systematically older ages calculated from lithium
depletion isochrones than from the HR diagram. We suggest that this discrepancy
may be related to the discrepancy between measured M-dwarf radii and the
smaller radii predicted by evolutionary models.Comment: Accepted by ApJ; 21 pages, 5 figure
HST/STIS Spectroscopy of the Lyman-Alpha Emission Line in the Central Dominant Galaxies in A426, A1795, and A2597: Constraints on Clouds in the Intracluster Medium
We report on HST/STIS spectra of the Lyman-alpha emission in the central
dominant galaxies in three rich clusters of galaxies. We find evidence for a
population of clouds in the intracluster medium.We detect 10 Ly-alpha
absorption systems towards the nucleus of NGC1275 with columns of N(HI)
1E12-1E14 cm-2. The detected absorption features are most consistent with
associated nuclear absorption systems. There is very little nuclear absorption
at the systemic velocity in NGC1275. This implies that the large columns
detected in the 21 cm line towards the parsec scale radio source avoid the line
of sight to the nucleus. This gas may be located in a circumnuclear disk or
torus. We detect at least one and possibly two absorption features towards the
extended Ly-alpha in A426. We do not detect absorption towards the extended
Ly-alpha emission in A1795, and A2597 with upper limits N(HI) 1E13 cm-2 for
optically thin absorbers. Our data constrain the covering factor of any high
column density gas in the ICM to be less than 25%. Our results suggest that the
lack of observed intermediate temperature gas is not explained by obscuration.
In addition, the low columns of gas on the 100 kpc scales in the ICM suggests
that (1) the rate at which cold gas accumulates in the ICM on these scales is
very low, and (2) the dense nebulae in the central 10 kpc must have cooled or
been deposited in situ.Comment: 6 figure
Asteroseismology of the open clusters NGC 6791, NGC 6811, and NGC 6819 from nineteen months of Kepler photometry
We studied solar-like oscillations in 115 red giants in the three open
clusters NGC 6791, NGC 6811, and NGC 6819, based on photometric data covering
more than 19 months with NASA's Kepler space telescope. We present the
asteroseismic diagrams of the asymptotic parameters \delta\nu_02, \delta\nu_01
and \epsilon, which show clear correlation with fundamental stellar parameters
such as mass and radius. When the stellar populations from the clusters are
compared, we see evidence for a difference in mass of the red giant branch
stars, and possibly a difference in structure of the red clump stars, from our
measurements of the small separations \delta\nu_02 and \delta\nu_01. Ensemble
\'{e}chelle diagrams and upper limits to the linewidths of l = 0 modes as a
function of \Delta\nu of the clusters NGC 6791 and NGC 6819 are also shown,
together with the correlation between the l = 0 ridge width and the T_eff of
the stars. Lastly, we distinguish between red giant branch and red clump stars
through the measurement of the period spacing of mixed dipole modes in 53 stars
among all the three clusters to verify the stellar classification from the
color-magnitude diagram. These seismic results also allow us to identify a
number of special cases, including evolved blue stragglers and binaries, as
well as stars in late He-core burning phases, which can be potentially
interesting targets for detailed theoretical modeling.Comment: 30 pages, 15 figures, 1 table, accepted to Ap
How are hygiene programmes designed in crises? Qualitative interviews with humanitarians in the Democratic Republic of the Congo and Iraq
BACKGROUND: Hygiene behaviour change programmes are complex to design. These challenges are heightened during crises when humanitarian responders are under pressure to implement programmes rapidly despite having limited information about the local situation, behaviours and opinions-all of which may also be rapidly evolving. METHODS: We conducted in-depth interviews with 36 humanitarian staff involved in hygiene programme design in two crisis-affected settings-one a conflict affected setting (Iraq) and the other amid a cholera outbreak (Democratic Republic of the Congo). Interviews explored decision-making in each phase of the humanitarian project cycle and were thematically analysed. RESULTS: Participants considered the design and implementation of hygiene programmes in crises to be sub-optimal. Humanitarians faced sector-specific challenges as well as more general constraints associated with operating within the humanitarian system. Programme-design decisions were made naturalistically and relied heavily on the intuitions and assumptions of senior staff. National organisations were often side-lined from programme design processes despite being in a better position to gather situational data. Consequently, programme design and decision-making processes adopted by humanitarians were similar across the two settings studied and led to similar types of hygiene promotion activities being delivered. CONCLUSION: Hygiene programming in crises-affected settings could be strengthened by initiatives targeted at supporting humanitarian staff during the pre-implementation programme design phase. This may include rapid assessment tools to better understand behavioural determinants in crisis-affected contexts; the use of a theory of change to inform the selection of programme activities; and funding mechanisms which encourage equitable partnerships, phased programming, regular adaptation and have programmatic components targeted at sustainability and sector capacity building. Initiatives aimed at sector reform should be cognisant of inter and intra-organisational dynamics, the ways that expertise is created and valued by the sector, and humanitarian habits and norms that arise in response to system constraints and pressures. These micro-organisational processes affect macro-level outcomes related to programme quality and acceptability and determine or limit the roles of national actors in programme design processes
Automated eukaryotic gene structure annotation using EVidenceModeler and the Program to Assemble Spliced Alignments
EVidenceModeler (EVM) is an automated annotation tool that predicts protein-coding regions, alternatively spliced transcripts and untranslated regions of eukaryotic genes
Translating research into practice: Protocol for a community-engaged, stepped wedge randomized trial to reduce disparities in breast cancer treatment through a regional patient navigation collaborative
BACKGROUND: Racial and socioeconomic disparities in breast cancer mortality persist. In Boston, MA, Black, Non-Hispanic women and Medicaid-insured individuals are 2-3 times more likely to have delays in treatment compared to White or privately insured women. While evidence-based care coordination strategies for reducing delays exist, they are not systematically implemented across healthcare settings.
METHODS: Translating Research Into Practice (TRIP) utilizes community engaged research methods to address breast cancer care delivery disparities. Four Massachusetts Clinical and Translational Science Institute (CTSI) hubs collaborated with the Boston Breast Cancer Equity Coalition (The Coalition) to implement an evidence-based care coordination intervention for Boston residents at risk for delays in breast cancer care. The Coalition used a community-driven process to define the problem of care delivery disparities, identify the target population, and develop a rigorous pragmatic approach. We chose a cluster-randomized, stepped-wedge hybrid type I effectiveness-implementation study design. The intervention implements three evidence-based strategies: patient navigation services, a shared patient registry for use across academic medical centers, and a web-based social determinants of health platform to identify and address barriers to care. Primary clinical outcomes include time to first treatment and receipt of guideline-concordant treatment, which are captured through electronic health records abstraction. We will use mixed methods to collect the secondary implementation outcomes of acceptability, adoption/penetration, fidelity, sustainability and cost.
CONCLUSION: TRIP utilizes an innovative community-driven research strategy, focused on interdisciplinary collaborations, to design and implement a translational science study that aims to more efficiently integrate proven health services interventions into clinical practice
Q methodology and a Delphi poll: a useful approach to researching a narrative approach to therapy
Q methodology and a Delphi poll combined qualitative and quantitative methods to explore definitions of White and Epston's (1990) narrative approach to therapy among a group of UK practitioners. A Delphi poll was used to generate statements about narrative therapy. The piloting of statements by the Delphi panel identified agreement about theoretical ideas underpinning narrative therapy and certain key practices. A wider group of practitioners ranked the statements in a Q sort and made qualitative comments about their sorting. Quantitative methods (principal components analysis) were used to extract eight accounts of narrative therapy, five of which are qualitatively analysed in this paper. Agreement and differences were identified across a range of issues, including the social construction of narratives, privileging a political stance or narrative techniques and the relationship with other therapies, specifically systemic psychotherapy. Q methodology, combined with the Delphi poll, was a unique and innovative feature of this study
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