5,535 research outputs found
Inherent-Structure Dynamics and Diffusion in Liquids
The self-diffusion constant D is expressed in terms of transitions among the
local minima of the potential (inherent structure, IS) and their correlations.
The formulae are evaluated and tested against simulation in the supercooled,
unit-density Lennard-Jones liquid. The approximation of uncorrelated
IS-transition (IST) vectors, D_{0}, greatly exceeds D in the upper temperature
range, but merges with simulation at reduced T ~ 0.50. Since uncorrelated IST
are associated with a hopping mechanism, the condition D ~ D_{0} provides a new
way to identify the crossover to hopping. The results suggest that theories of
diffusion in deeply supercooled liquids may be based on weakly correlated IST.Comment: submitted to PR
Muon spin rotation studies of niobium for superconducting RF applications
In this work we investigate superconducting properties of niobium samples via
application of the muon spin rotation/relaxation (muSR) technique. We employ
for the first time the muSR technique to study samples that are cutout from
large and small grain 1.5 GHz radio frequency (RF) single cell niobium
cavities. The RF test of these cavities was accompanied by full temperature
mapping to characterize the RF losses in each of the samples. Results of the
muSR measurements show that standard cavity surface treatments like mild baking
and buffered chemical polishing (BCP) performed on the studied samples affect
their surface pinning strength. We find an interesting correlation between high
field RF losses and field dependence of the sample magnetic volume fraction
measured via muSR. The muSR line width observed in ZF-muSR measurements matches
the behavior of Nb samples doped with minute amounts of Ta or N impurities. An
upper bound for the upper critical field Hc2 of these cutouts is found.Comment: 20 pages, 14 figure
Protocol for the United Kingdom Rotator Cuff Study (UKUFF) : a randomised controlled trial of open and arthroscopic rotator cuff repair
This project was funded by the NIHR Health Technology Assessment programme (project number 05/47/02). J. L. Rees has received a grant from Oxford University which is related to this paper. J. Dawson reports that Oxford University has received a grant from HTA which is related to this paper, as well as a study grant.Peer reviewedPublisher PD
Molecular Identification of Eimeria Species in Broiler Chickens in Trinidad, West Indies
Coccidiosis is an intestinal disease of chickens of major economic importance to broiler industries worldwide. Species of coccidia found in chickens include Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, and Eimeria tenella. In recent years, polymerase chain reaction (PCR) has been developed to provide accurate and rapid identification of the seven known Eimeria species of chickens. The aim of this study was to use species-specific real-time PCR (qPCR) to identify which of the seven Eimeria species are present in Trinidad poultry. Seventeen pooled fecal samples were collected from 6 broiler farms (2–5 pens per farm) across Trinidad. Feces were also collected from birds showing clinical signs of coccidiosis in two live bird markets (pluck shops). qPCR revealed the presence of five species of Eimeria (E. acervulina, E. maxima, E. mitis, E. necatrix, and E. tenella), but not E. brunetti or E. praecox. Mixed infections were detected on all broiler farms, and DNA of two highly pathogenic Eimeria species (E. tenella and E. necatrix) was detected in feces taken from clinically sick birds sampled from the two pluck shops
Does the addition of a supportive chatbot promote user engagement with a smoking cessation app? An experimental study
Does the addition of a supportive chatbot promote user engagement with a smoking cessation app? An experimental study
Show all authors
Olga Perski, David Crane, Emma Beard, ...
First Published September 30, 2019 Research Article
https://doi.org/10.1177/2055207619880676
Article information
Article has an altmetric score of 27 Open AccessCreative Commons Attribution 4.0 License
Abstract
Objective
The objective of this study was to assess whether a version of the Smoke Free app with a supportive chatbot powered by artificial intelligence (versus a version without the chatbot) led to increased engagement and short-term quit success.
Methods
Daily or non-daily smokers aged ≥18 years who purchased the ‘pro’ version of the app and set a quit date were randomly assigned (unequal allocation) to receive the app with or without the chatbot. The outcomes were engagement (i.e. total number of logins over the study period) and self-reported abstinence at a one-month follow-up. Unadjusted and adjusted negative binomial and logistic regression models were fitted to estimate incidence rate ratios (IRRs) and odds ratios (ORs) for the associations of interest.
Results
A total of 57,214 smokers were included (intervention: 9.3% (5339); control: 90.7% (51,875). The app with the chatbot compared with the standard version led to a 101% increase in engagement (IRRadj = 2.01, 95% confidence interval (CI) = 1.92–2.11, p < .001). The one-month follow-up rate was 10.6% (intervention: 19.9% (1,061/5,339); control: 9.7% (5,050/51,875). Smokers allocated to the intervention had greater odds of quit success (missing equals smoking: 844/5,339 vs. 3,704/51,875, ORadj = 2.38, 95% CI = 2.19–2.58, p < .001; follow-up only: 844/1,061 vs. 3,704/5,050, ORadj = 1.36, 95% CI = 1.16–1.61, p < .001).
Conclusion
The addition of a supportive chatbot to a popular smoking cessation app more than doubled user engagement. In view of very low follow-up rates, there is low quality evidence that the addition also increased self-reported smoking cessation
The Inferred Cardiogenic Gene Regulatory Network in the Mammalian Heart
Cardiac development is a complex, multiscale process encompassing cell fate adoption, differentiation and morphogenesis. To elucidate pathways underlying this process, a recently developed algorithm to reverse engineer gene regulatory networks was applied to time-course microarray data obtained from the developing mouse heart. Approximately 200 genes of interest were input into the algorithm to generate putative network topologies that are capable of explaining the experimental data via model simulation. To cull specious network interactions, thousands of putative networks are merged and filtered to generate scale-free, hierarchical networks that are statistically significant and biologically relevant. The networks are validated with known gene interactions and used to predict regulatory pathways important for the developing mammalian heart. Area under the precision-recall curve and receiver operator characteristic curve are 9% and 58%, respectively. Of the top 10 ranked predicted interactions, 4 have already been validated. The algorithm is further tested using a network enriched with known interactions and another depleted of them. The inferred networks contained more interactions for the enriched network versus the depleted network. In all test cases, maximum performance of the algorithm was achieved when the purely data-driven method of network inference was combined with a data-independent, functional-based association method. Lastly, the network generated from the list of approximately 200 genes of interest was expanded using gene-profile uniqueness metrics to include approximately 900 additional known mouse genes and to form the most likely cardiogenic gene regulatory network. The resultant network supports known regulatory interactions and contains several novel cardiogenic regulatory interactions. The method outlined herein provides an informative approach to network inference and leads to clear testable hypotheses related to gene regulation
QCD as a Quantum Link Model
QCD is constructed as a lattice gauge theory in which the elements of the
link matrices are represented by non-commuting operators acting in a Hilbert
space. The resulting quantum link model for QCD is formulated with a fifth
Euclidean dimension, whose extent resembles the inverse gauge coupling of the
resulting four-dimensional theory after dimensional reduction. The inclusion of
quarks is natural in Shamir's variant of Kaplan's fermion method, which does
not require fine-tuning to approach the chiral limit. A rishon representation
in terms of fermionic constituents of the gluons is derived and the quantum
link Hamiltonian for QCD with a U(N) gauge symmetry is expressed in terms of
glueball, meson and constituent quark operators. The new formulation of QCD is
promising both from an analytic and from a computational point of view.Comment: 27 pages, including three figures. ordinary LaTeX; Submitted to Nucl.
Phys.
Ultrafast supercontinuum spectroscopy of carrier multiplication and biexcitonic effects in excited states of PbS quantum dots
We examine the multiple exciton population dynamics in PbS quantum dots by
ultrafast spectrally-resolved supercontinuum transient absorption (SC-TA). We
simultaneously probe the first three excitonic transitions over a broad
spectral range. Transient spectra show the presence of first order bleach of
absorption for the 1S_h-1S_e transition and second order bleach along with
photoinduced absorption band for 1P_h-1P_e transition. We also report evidence
of the one-photon forbidden 1S_{h,e}-1P_{h,e} transition. We examine signatures
of carrier multiplication (multiexcitons for the single absorbed photon) from
analysis of the first and second order bleaches, in the limit of low absorbed
photon numbers (~ 10^-2), at pump energies from two to four times the
semiconductor band gap. The multiexciton generation efficiency is discussed
both in terms of a broadband global fit and the ratio between early- to
long-time transient absorption signals.. Analysis of population dynamics shows
that the bleach peak due to the biexciton population is red-shifted respect the
single exciton one, indicating a positive binding energy.Comment: 16 pages, 5 figure
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