3,685 research outputs found
Making Sense of a New Transport System: An Ethnographic Study of the Cambridgeshire Guided Busway
An increase in public transport use has the potential to contribute to improving population health, and there is growing interest in innovative public transport systems. Yet how new public transport infrastructure is experienced and integrated (or not) into daily practice is little understood. We investigated how the Cambridgeshire Guided Busway, UK, was used and experienced in the weeks following its opening, using the method of participant observation (travelling on the busway and observing and talking to passengers) and drawing on Normalization Process Theory to interpret our data. Using excerpts of field notes to support our interpretations, we describe how the ease with which the new transport system could be integrated into existing daily routines was important in determining whether individuals would continue to use it. It emerged that there were two groups of passengers with different experiences and attitudes. Passengers who had previously travelled frequently on regular bus services did not perceive the new system to be an improvement; consequently, they were frustrated that it was differentiated from and not coherent with the regular system. In contrast, passengers who had previously travelled almost exclusively by car appraised the busway positively and perceived it to be a novel and superior form of travel. Our rich qualitative account highlights the varied and creative ways in which people learn to use new public transport and integrate it into their everyday lives. This has consequences for the introduction and promotion of future transport innovations. It is important to emphasise the novelty of new public transport, but also the ways in which its use can become ordinary and routine. Addressing these issues could help to promote uptake of other public transport interventions, which may contribute to increasing physical activity and improving population health. © 2013 Jones et al
New Equations for Neutral Terms: A Sound and Complete Decision Procedure, Formalized
The definitional equality of an intensional type theory is its test of type
compatibility. Today's systems rely on ordinary evaluation semantics to compare
expressions in types, frustrating users with type errors arising when
evaluation fails to identify two `obviously' equal terms. If only the machine
could decide a richer theory! We propose a way to decide theories which
supplement evaluation with `-rules', rearranging the neutral parts of
normal forms, and report a successful initial experiment.
We study a simple -calculus with primitive fold, map and append operations on
lists and develop in Agda a sound and complete decision procedure for an
equational theory enriched with monoid, functor and fusion laws
Structured Matrix Completion with Applications to Genomic Data Integration
Matrix completion has attracted significant recent attention in many fields
including statistics, applied mathematics and electrical engineering. Current
literature on matrix completion focuses primarily on independent sampling
models under which the individual observed entries are sampled independently.
Motivated by applications in genomic data integration, we propose a new
framework of structured matrix completion (SMC) to treat structured missingness
by design. Specifically, our proposed method aims at efficient matrix recovery
when a subset of the rows and columns of an approximately low-rank matrix are
observed. We provide theoretical justification for the proposed SMC method and
derive lower bound for the estimation errors, which together establish the
optimal rate of recovery over certain classes of approximately low-rank
matrices. Simulation studies show that the method performs well in finite
sample under a variety of configurations. The method is applied to integrate
several ovarian cancer genomic studies with different extent of genomic
measurements, which enables us to construct more accurate prediction rules for
ovarian cancer survival.Comment: Accepted for publication in Journal of the American Statistical
Associatio
Pharmacologically blocking p53-dependent apoptosis protects intestinal stem cells and mice from radiation.
Exposure to high levels of ionizing radiation (IR) leads to debilitating and dose-limiting gastrointestinal (GI) toxicity. Using three-dimensional mouse crypt culture, we demonstrated that p53 target PUMA mediates radiation-induced apoptosis via a cell-intrinsic mechanism, and identified the GSK-3 inhibitor CHIR99021 as a potent radioprotector. CHIR99021 treatment improved Lgr5+ cell survival and crypt regeneration after radiation in culture and mice. CHIR99021 treatment specifically blocked apoptosis and PUMA induction and K120 acetylation of p53 mediated by acetyl-transferase Tip60, while it had no effect on p53 stabilization, phosphorylation or p21 induction. CHIR99021 also protected human intestinal cultures from radiation by PUMA but not p21 suppression. These results demonstrate that p53 posttranslational modifications play a key role in the pathological and apoptotic response of the intestinal stem cells to radiation and can be targeted pharmacologically
Statistical modeling of causal effects in continuous time
This article studies the estimation of the causal effect of a time-varying
treatment on time-to-an-event or on some other continuously distributed
outcome. The paper applies to the situation where treatment is repeatedly
adapted to time-dependent patient characteristics. The treatment effect cannot
be estimated by simply conditioning on these time-dependent patient
characteristics, as they may themselves be indications of the treatment effect.
This time-dependent confounding is common in observational studies. Robins
[(1992) Biometrika 79 321--334, (1998b) Encyclopedia of Biostatistics 6
4372--4389] has proposed the so-called structural nested models to estimate
treatment effects in the presence of time-dependent confounding. In this
article we provide a conceptual framework and formalization for structural
nested models in continuous time. We show that the resulting estimators are
consistent and asymptotically normal. Moreover, as conjectured in Robins
[(1998b) Encyclopedia of Biostatistics 6 4372--4389], a test for whether
treatment affects the outcome of interest can be performed without specifying a
model for treatment effect. We illustrate the ideas in this article with an
example.Comment: Published in at http://dx.doi.org/10.1214/009053607000000820 the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The Deep Diffuse Extragalactic Radio Sky at 1.75 GHz
We present a study of diffuse extragalactic radio emission at GHz
from part of the ELAIS-S1 field using the Australia Telescope Compact Array.
The resulting mosaic is deg, with a roughly constant noise region
of deg used for analysis. The image has a beam size of arcsec and instrumental Jy beam. Using point-source models from the ATLAS survey, we
subtract the discrete emission in this field for Jy
beam. Comparison of the source-subtracted probability distribution, or
\pd, with the predicted distribution from unsubtracted discrete emission and
noise, yields an excess of Jy beam. Taking this as
an upper limit on any extended emission we constrain several models of extended
source counts, assuming arcmin. The best-fitting
models yield temperatures of the radio background from extended emission of
mK, giving an upper limit on the total temperature at
GHz of mK. Further modelling shows that our data are
inconsistent with the reported excess temperature of ARCADE2 to a source-count
limit of Jy. Our new data close a loop-hole in the previous
constraints, because of the possibility of extended emission being resolved out
at higher resolution. Additionally, we look at a model of cluster halo emission
and two WIMP dark matter annihilation source-count models, and discuss general
constraints on any predicted counts from such sources. Finally, we report the
derived integral count at GHz using the deepest discrete count plus our
new extended-emission limits, providing numbers that can be used for planning
future ultra-deep surveys.Comment: 18 pages, 15 figures, 7 tables, Accepted by MNRA
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