44 research outputs found
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
Planck early results III : First assessment of the Low Frequency Instrument in-flight performance
Peer reviewe
Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future
Purpose Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future. Design Meta-analysis of prevalence data. Participants A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe. Methods AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV). Main Outcome Measures Prevalence of early and late AMD, BCVA, and number of AMD cases. Results Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%–5.0%) in those aged 55–59 years to 17.6% (95%
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Passive Q-switching and mode-locking for the generation of nanosecond to femtosecond pulses
Correctable visual impairment in stroke rehabilitation patients
BACKGROUND: after stroke, visual impairment may exacerbate the impact of other impairments on overall disability and negatively influence rehabilitation.OBJECTIVE: to examine the visual status of patients after stroke and determine whether this can be improved by simple interventions.DESIGN: prospective study.SETTINGS: stroke rehabilitation unit in a Belfast teaching hospital.SUBJECTS: 77 consecutive patients admitted for rehabilitation after acute stroke. Methods: full optometric and ophthalmic assessment within 2 weeks of admission.RESULTS: of 70 patients with glasses, 19 did not have their glasses in hospital before prompting and 18 had glasses in unacceptable condition. Twenty patients had impaired visual acuity (6/12 or worse) with existing glasses (if helpful); 11 of these improved to better than 6/12 with refractive correction.CONCLUSIONS: stroke professionals need to enquire about patients' spectacles and assess their condition. Patients with reduced visual acuity in the absence of significant non-refractive disease should be referred to an optometrist: in this series 14% of patients had visual impairment which benefited from refractive correction
A channel model for the propagation of X-band radio waves through the solar corona
Spacecraft communication systems operating at X-band are strongly affected when the propagation path passes close to the sun (characterised by the Sun-Earth-Probe, SEP, angle). In this paper, a channel model that can generate a time-series of signal amplitude and phase is presented. The channel model reproduces the observations well for SEP>2° and, with some caveats, works at smaller values of SEP. © 2017 Institution of Engineering and Technology. All rights reserved
An X Band Radio Channel Model for Propagation Through the Solar Corona
Spacecraft communication systems operating at X band are strongly affected when the propagation path passes close to the Sun (which can be characterized by the Sun-Earth-Probe, SEP, angle). In this paper, a channel model that can generate a time series of signal amplitude and phase, and hence the signal in-phase and quadrature values, is presented. For X band, the channel model reproduces the observations well for SEP > 0.8°. While the model has not been experimentally validated at SEP angles below 0.8°, the behavior is consistent with measurements reported in the literature and is therefore likely to be suitable for use, with caution, in that region too. ©2018. American Geophysical Union. All Rights Reserved