Noise-enabled precision measurements of a Duffing nanomechanical resonator

We report quantitative experimental measurements of the nonlinear response of a radiofrequency mechanical resonator, with very high quality factor, driven by a large swept-frequency force. We directly measure the noise-free transition dynamics between the two basins of attraction that appear in the nonlinear regime, and find good agreement with those predicted by the one-dimensional Duffing equation of motion. We then measure the response of the transition rates to controlled levels of white noise, and extract the activation energy from each basin. The measurements of the noise-induced transitions allow us to obtain precise values for the critical frequencies, the natural resonance frequency, and the cubic nonlinear parameter in the Duffing oscillator, with direct applications to high sensitivity parametric sensors based on these resonators.Comment: 5 pages, 5 figure

Code sets for respiratory symptoms in electronic health records (EHR) research: a systematic review protocol

Introduction Asthma and chronic obstructive pulmonary disease (COPD) are common respiratory conditions, which result in significant morbidity worldwide. These conditions are associated with a range of non-specific symptoms, which in themselves are a target for health research. Such research is increasingly being conducted using electronic health records (EHRs), but computable phenotype definitions, in the form of code sets or code lists, are required to extract structured data from these large routine databases in a systematic and reproducible way. The aim of this protocol is to specify a systematic review to identify code sets for respiratory symptoms in EHRs research. Methods and analysis MEDLINE and Embase databases will be searched using terms relating to EHRs, respiratory symptoms and use of code sets. The search will cover all English-language studies in these databases between January 1990 and December 2017. Two reviewers will independently screen identified studies for inclusion, and key data will be extracted into a uniform table, facilitating cross-comparison of codes used. Disagreements between the reviewers will be adjudicated by a third reviewer. This protocol has been produced in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol guidelines. Ethics and dissemination As a review of previously published studies, no ethical approval is required. The results of this review will be submitted to a peer-reviewed journal for publication and can be used in future research into respiratory symptoms that uses electronic healthcare databases

Dedicated outreach service for hard to reach patients with tuberculosis in London: observational study and economic evaluation.

OBJECTIVE: To assess the cost effectiveness of the Find and Treat service for diagnosing and managing hard to reach individuals with active tuberculosis. DESIGN: Economic evaluation using a discrete, multiple age cohort, compartmental model of treated and untreated cases of active tuberculosis. SETTING: London, United Kingdom. Population Hard to reach individuals with active pulmonary tuberculosis screened or managed by the Find and Treat service (48 mobile screening unit cases, 188 cases referred for case management support, and 180 cases referred for loss to follow-up), and 252 passively presenting controls from London's enhanced tuberculosis surveillance system. MAIN OUTCOME MEASURES: Incremental costs, quality adjusted life years (QALYs), and cost effectiveness ratios for the Find and Treat service. RESULTS: The model estimated that, on average, the Find and Treat service identifies 16 and manages 123 active cases of tuberculosis each year in hard to reach groups in London. The service has a net cost of £1.4 million/year and, under conservative assumptions, gains 220 QALYs. The incremental cost effectiveness ratio was £6400-£10,000/QALY gained (about €7300-€11,000 or $10,000-$16 000 in September 2011). The two Find and Treat components were also cost effective, even in unfavourable scenarios (mobile screening unit (for undiagnosed cases), £18,000-£26,000/QALY gained; case management support team, £4100-£6800/QALY gained). CONCLUSIONS: Both the screening and case management components of the Find and Treat service are likely to be cost effective in London. The cost effectiveness of the mobile screening unit in particular could be even greater than estimated, in view of the secondary effects of infection transmission and development of antibiotic resistance

Causes of hospital admission and mortality among 6683 people who use heroin: a cohort study comparing relative and absolute risks

Background: Mortality in high-risk groups such as people who use illicit drugs is often expressed in relative terms such as standardised ratios. These measures are highest for diseases that are rare in the general population, such as hepatitis C, and may understate the importance of common long-term conditions. Population: 6683 people in community-based treatment for heroin dependence between 2006 and 2017 in London, England, linked to national hospital and mortality databases with 55,683 years of follow-up. Method: Age- and sex-specific mortality and hospital admission rates in the general population of London were used to calculate the number of expected events. We compared standardised ratios (relative risk) to excess deaths and admissions (absolute risk) across ICD-10 chapters and subcategories. Results: Drug-related diseases had the highest relative risks, with a standardised mortality ratio (SMR) of 48 (95% CI 42–54) and standardised admission ratio (SAR) of 293 (95% CI 282–304). By contrast, other diseases had an SMR of 4.4 (95% CI 4.0–4.9) and an SAR of 3.15 (95% CI 3.11–3.19). However, the majority of the 621 excess deaths (95% CI 569–676) were not drug-related (361; 58%). The largest groups were liver disease (75 excess deaths) and COPD (45). Similarly, 80% (11,790) of the 14,668 excess admissions (95% CI 14,382–14,957) were not drug-related. The largest groups were skin infections (1073 excess admissions), alcohol (1060), COPD (812) and head injury (612). Conclusions: Although relative risks of drug-related diseases are very high, most excess morbidity and mortality in this cohort was caused by common long-term conditions

Applications of graphics to support a testbed for autonomous space vehicle operations

Researchers describe their experience using graphics tools and utilities while building an application, AUTOPS, that uses a graphical Machintosh (TM)-like interface for the input and display of data, and animation graphics to enhance the presentation of results of autonomous space vehicle operations simulations. AUTOPS is a test bed for evaluating decisions for intelligent control systems for autonomous vehicles. Decisions made by an intelligent control system, e.g., a revised mission plan, might be displayed to the user in textual format or he can witness the effects of those decisions via out of window graphics animations. Although a textual description conveys essentials, a graphics animation conveys the replanning results in a more convincing way. Similarily, iconic and menu-driven screen interfaces provide the user with more meaningful options and displays. Presented here are experiences with the SunView and TAE Plus graphics tools used for interface design, and the Johnson Space Center Interactive Graphics Laboratory animation graphics tools used for generating out out of the window graphics

Siren songs or path to salvation? Interpreting the visions of web technology at a UK regional newspaper in crisis, 2006-11

A 5-year case study of an established regional newspaper in Britain investigates journalists about their perceptions of convergence in digital technologies. This research is the first ethnographic longitudinal case study of a UK regional newspaper. Although conforming to some trends observed in the wider field of scholarship, the analysis adds to skepticism about any linear or directional views of innovation and adoption: the Northern Echo newspaper journalists were observed to have revised their opinions of optimum Web practices, and sometimes radically reversed policies. Technology is seen in the period as a fluid, amorphous entity. Central corporate authority appeared to diminish in the period as part of a wider reduction in formalism. Questioning functionalist notions of the market, the study suggests cause and effect models of change are often subverted by contradictory perceptions of particular actions. Meanwhile, during technological evolution, the ‘professional imagination’ can be understood as strongly reflecting the parent print culture and its routines, despite pioneering a new convergence partnership with an independent television company

Investigating the Stratigraphy of an Alluvial Aquifer Using Crosswell Seismic Traveltime Tomography

In this study, we investigate the use of crosswell P-wave seismic tomography to obtain spatially extensive information about subsurface sedimentary architecture and heterogeneity in alluvial aquifers. Our field site was a research wellfield in an unconfined aquifer near Boise, Idaho. The aquifer consists of a ~ 20-m-thick sequence of alluvial cobble- and-sand deposits, which have been subdivided into five stratigraphic units based on neutron porosity logs, grainsize analysis, and radar reflection data. We collected crosswell and borehole-to-surface seismic data in wells 17.1 m apart. We carefully considered the impact of well deviation, data quality control, and the choice of inversion parameters. Our linearized inverse routine had a curved-ray forward model and used different grids for forward modeling and inversion. An analysis of the model covariance and resolution matrices showed that the velocity models had an uncertainty of \u3c10 m\u3e/s, a vertical resolution of ~ 1 m, and a horizontal resolution of ~ 5 m. The velocity in the saturated zone varied between 2100 m/s and 2700 m/s. Inclusion of the borehole-to-surface data eliminated the Xshaped pattern that is a common artifact in crosswell tomography, and the increased angular coverage also improved the accuracy of the model near the top of the tomogram. The final velocity model is consistent with previous stratigraphic analyses of the site, although the locations of some of the unit boundaries differ by as much as 2 m in places. The results of this study demonstrate that seismic tomography can be used to image the sedimentary architecture of unconsolidated alluvial aquifers, even when the lithologic contrasts between units are subtle

Point-of-care screening for a current Hepatitis C virus infection: influence on uptake of a concomitant offer of HIV screening

Eliminating hepatitis C as a public health threat requires an improved understanding of how to increase testing uptake. We piloted point-of-care testing (POCT) for a current HCV infection in an inner-city Emergency Department (ED) and assessed the influence on uptake of offering concomitant screening for HIV. Over four months, all adults attending ED with minor injuries were first invited to complete an anonymous questionnaire then invited to test in alternating cycles offering HCV POCT or HCV+HIV POCT. Viral RNA was detected in finger-prick blood by GeneXpert. 814/859 (94.8%) questionnaires were returned and 324/814 (39.8%) tests were accepted, comprising 211 HCV tests and 113 HCV+HIV tests. Offering concomitant HIV screening reduced uptake after adjusting for age and previous HCV testing (odds ratio 0.51; 95% confidence interval [CI] 0.38–0.68; p < 0.001). HCV prevalence was 1/324 (0.31%; 95% CI 0.05–1.73); no participant tested positive for HIV. 167/297 (56.2%) POCT participants lived in the most deprived neighbourhoods in England. HCV RNA testing using finger-prick blood was technically feasible. Uptake was moderate and the offer of concomitant HIV screening showed a detrimental impact on acceptability in this low prevalence population. The findings should be confirmed in a variety of other community settings