156 research outputs found
The Role of Source Coherence in Atom Interferometery
The role of source cloud spatial coherence in a Mach-Zehnder type atom
interferometer is experimentally investigated. The visibility and contrast of a
Bose-Einstein condensate (BEC) and three thermal sources with varying spatial
coherence are compared as a function of interferometer time. At short times,
the fringe visibility of a BEC source approaches 100 % nearly independent of pi
pulse efficiency, while thermal sources have fringe visibilities limited to the
mirror efficiency. More importantly for precision measurement systems, the BEC
source maintains interference at interferometer times significantly beyond the
thermal source
Remote triage incorporating symptom-based risk stratification for suspected head and neck cancer referrals:A prospective population-based study
80hk Momentum Separation with Bloch Oscillations in an Optically Guided Atom Interferometer
We demonstrate phase sensitivity in a horizontally guided,
acceleration-sensitive atom interferometer with a momentum separation of 80hk
between its arms. A fringe visibility of 7% is observed. Our coherent pulse
sequence accelerates the cold cloud in an optical waveguide, an inherently
scalable route to large momentum separation and high sensitivity. We maintain
coherence at high momentum separation due to both the transverse confinement
provided by the guide, and our use of optical delta-kick cooling on our
cold-atom cloud. We also construct a horizontal interferometric gradiometer to
measure the longitudinal curvature of our optical waveguide.Comment: 6 pages, 6 figure
A Bright Solitonic Matter-Wave Interferometer
We present the first realisation of a solitonic atom interferometer. A
Bose-Einstein condensate of atoms of rubidium-85 is loaded into a
horizontal optical waveguide. Through the use of a Feshbach resonance, the
-wave scattering length of the Rb atoms is tuned to a small negative
value. This attractive atomic interaction then balances the inherent
matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder
interferometer is constructed by driving Bragg transitions with the use of an
optical lattice co-linear with the waveguide. Matter wave propagation and
interferometric fringe visibility are compared across a range of -wave
scattering values including repulsive, attractive and non-interacting values.
The solitonic matter wave is found to significantly increase fringe visibility
even compared with a non-interacting cloud.Comment: 6 pages, 4 figure
A quantum sensor: simultaneous precision gravimetry and magnetic gradiometry with a Bose-Einstein condensate
A Bose-Einstein condensate is used as an atomic source for a high precision
sensor. A atom F=1 spinor condensate of Rb is released
into free fall for up to ms and probed with a Mach-Zehnder atom
interferometer based on Bragg transitions. The Bragg interferometer
simultaneously addresses the three magnetic states, , facilitating a simultaneous measurement of the acceleration due
to gravity with an asymptotic precision of g/g and
the magnetic field gradient to a precision pT/m
Non-destructive shadowgraph imaging of ultracold atoms
An imaging system is presented that is capable of far-detuned non-destructive
imaging of a Bose-Einstein condensate with the signal proportional to the
second spatial derivative of the density. Whilst demonstrated with application
to , the technique generalizes to other atomic species and is
shown to be capable of a signal to noise of at GHz detuning with
in-trap images showing no observable heating or atom loss. The technique
is also applied to the observation of individual trajectories of stochastic
dynamics inaccessible to single shot imaging. Coupled with a fast optical phase
lock loop, the system is capable of dynamically switching to resonant
absorption imaging during the experiment.Comment: 4 pages, 5 figure
Admission avoidance in acute epistaxis: a prospective national audit during the initial peak of the COVID‐19 pandemic
OBJECTIVES: To report changes in practice brought about by COVID-19 and the implementation of new guidelines, and to explore factors relating to unscheduled re-presentations for patients discharged from the emergency department (ED). DESIGN: Prospective multicentre national audit over 12 weeks from 6th April 2020. SETTING: UK secondary care ENT departments. PARTICIPANTS: Adult patients with acute epistaxis. MAIN OUTCOME MEASURES: Re-presentation within 10 days for patients discharged from the ED. RESULTS: Eighty three centres from all four UK nations submitted 2631 valid cases. The majority of cases were ED referrals (89.7%, n = 2358/2631). 54.6% were discharged from the ED following ENT review (n = 1267/2322), of whom 19.5% re-presented within 10 days (n = 245/1259) and 6.8% were ultimately admitted (n = 86/1259). 46.7% of patients had a non-dissolvable pack inserted by ED prior to referral to ENT (n = 1099/2355). The discharge rates for ED patients and their subsequent re-presentation rates were as follows: non-dissolvable packs, 29.5% discharged (n = 332/1125), 18.2% re-presented (n = 60/330); dissolvable products, 71.1% discharged (n = 488/686), 21.8% re-presented (n = 106/486); cautery only, 89.2% discharged (n = 247/277), 20.0% re-presented (n = 49/245); and no intranasal intervention, 85.5% discharged (n = 200/234), 15.2% re-presented (n = 30/198). Univariable logistic regression showed that not being packed by ED, antiplatelet medications, failed cautery and recent epistaxis treatment were significant predictors of re-presentation within 10 days. CONCLUSIONS: Management of acute epistaxis was notably affected during the initial peak of the pandemic, with a shift towards reduced admissions. This national audit highlights that many patients who may previously have been admitted to hospital may be safely discharged from the ED following acute epistaxis
Novel functional view of the crocidolite asbestos-treated A549 human lung epithelial transcriptome reveals an intricate network of pathways with opposing functions
<p>Abstract</p> <p>Background</p> <p>Although exposure to asbestos is now regulated, patients continue to be diagnosed with mesothelioma, asbestosis, fibrosis and lung carcinoma because of the long latent period between exposure and clinical disease. Asbestosis is observed in approximately 200,000 patients annually and asbestos-related deaths are estimated at 4,000 annually<abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. Although advances have been made using single gene/gene product or pathway studies, the complexity of the response to asbestos and the many unanswered questions suggested the need for a systems biology approach. The objective of this study was to generate a comprehensive view of the transcriptional changes induced by crocidolite asbestos in A549 human lung epithelial cells.</p> <p>Results</p> <p>A statistically robust, comprehensive data set documenting the crocidolite-induced changes in the A549 transcriptome was collected. A systems biology approach involving global observations from gene ontological analyses coupled with functional network analyses was used to explore the effects of crocidolite in the context of known molecular interactions. The analyses uniquely document a transcriptome with function-based networks in cell death, cancer, cell cycle, cellular growth, proliferation, and gene expression. These functional modules show signs of a complex interplay between signaling pathways consisting of both novel and previously described asbestos-related genes/gene products. These networks allowed for the identification of novel, putative crocidolite-related genes, leading to several new hypotheses regarding genes that are important for the asbestos response. The global analysis revealed a transcriptome that bears signatures of both apoptosis/cell death and cell survival/proliferation.</p> <p>Conclusion</p> <p>Our analyses demonstrate the power of combining a statistically robust, comprehensive dataset and a functional network genomics approach to 1) identify and explore relationships between genes of known importance 2) identify novel candidate genes, and 3) observe the complex interplay between genes/gene products that function in seemingly different processes. This study represents the first function-based global approach toward understanding the response of human lung epithelial cells to the carcinogen crocidolite. Importantly, our investigation paints a much broader landscape for the crocidolite response than was previously appreciated and reveals novel paths to study. Our graphical representations of the function-based global network will be a valuable resource to model new research findings.</p
Search algorithms as a framework for the optimization of drug combinations
Combination therapies are often needed for effective clinical outcomes in the
management of complex diseases, but presently they are generally based on
empirical clinical experience. Here we suggest a novel application of search
algorithms, originally developed for digital communication, modified to
optimize combinations of therapeutic interventions. In biological experiments
measuring the restoration of the decline with age in heart function and
exercise capacity in Drosophila melanogaster, we found that search algorithms
correctly identified optimal combinations of four drugs with only one third of
the tests performed in a fully factorial search. In experiments identifying
combinations of three doses of up to six drugs for selective killing of human
cancer cells, search algorithms resulted in a highly significant enrichment of
selective combinations compared with random searches. In simulations using a
network model of cell death, we found that the search algorithms identified the
optimal combinations of 6-9 interventions in 80-90% of tests, compared with
15-30% for an equivalent random search. These findings suggest that modified
search algorithms from information theory have the potential to enhance the
discovery of novel therapeutic drug combinations. This report also helps to
frame a biomedical problem that will benefit from an interdisciplinary effort
and suggests a general strategy for its solution.Comment: 36 pages, 10 figures, revised versio
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