Modeling the partially coherent behavior of few-mode far-infrared grating spectrometers

Modelling ultra-low-noise far-infrared grating spectrometers has become crucial for the next generation of far-infrared space observatories. Conventional techniques are awkward to apply because of the partially coherent form of the incident spectral field, and the few-mode response of the optics and detectors. We present a modal technique for modelling the behaviour of spectrometers, which allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces. We illustrate the technique by modelling the behaviour of the Long Wavelength Band of the proposed SAFARI instrument on the well-studied SPICA mission.Comment: This paper is submitted to Journal Optical Society of America A. When accepted, the paper can be found here: https://opg.optica.org/josaa/home.cf

Toward engineering biosystems with emergent collective functions

Many complex behaviors in biological systems emerge from large populations of interacting molecules or cells, generating functions that go beyond the capabilities of the individual parts. Such collective phenomena are of great interest to bioengineers due to their robustness and scalability. However, engineering emergent collective functions is difficult because they arise as a consequence of complex multi-level feedback, which often spans many length-scales. Here, we present a perspective on how some of these challenges could be overcome by using multi-agent modeling as a design framework within synthetic biology. Using case studies covering the construction of synthetic ecologies to biological computation and synthetic cellularity, we show how multi-agent modeling can capture the core features of complex multi-scale systems and provide novel insights into the underlying mechanisms which guide emergent functionalities across scales. The ability to unravel design rules underpinning these behaviors offers a means to take synthetic biology beyond single molecules or cells and toward the creation of systems with functions that can only emerge from collectives at multiple scales

Low-mass pre--main-sequence stars in the Magellanic Clouds

[Abridged] The stellar Initial Mass Function (IMF) suggests that sub-solar stars form in very large numbers. Most attractive places for catching low-mass star formation in the act are young stellar clusters and associations, still (half-)embedded in star-forming regions. The low-mass stars in such regions are still in their pre--main-sequence (PMS) evolutionary phase. The peculiar nature of these objects and the contamination of their samples by the evolved populations of the Galactic disk impose demanding observational techniques for the detection of complete numbers of PMS stars in the Milky Way. The Magellanic Clouds, the companion galaxies to our own, demonstrate an exceptional star formation activity. The low extinction and stellar field contamination in star-forming regions of these galaxies imply a more efficient detection of low-mass PMS stars than in the Milky Way, but their distance from us make the application of special detection techniques unfeasible. Nonetheless, imaging with the Hubble Space Telescope yield the discovery of solar and sub-solar PMS stars in the Magellanic Clouds from photometry alone. Unprecedented numbers of such objects are identified as the low-mass stellar content of their star-forming regions, changing completely our picture of young stellar systems outside the Milky Way, and extending the extragalactic stellar IMF below the persisting threshold of a few solar masses. This review presents the recent developments in the investigation of PMS stars in the Magellanic Clouds, with special focus on the limitations by single-epoch photometry that can only be circumvented by the detailed study of the observable behavior of these stars in the color-magnitude diagram. The achieved characterization of the low-mass PMS stars in the Magellanic Clouds allowed thus a more comprehensive understanding of the star formation process in our neighboring galaxies.Comment: Review paper, 26 pages (in LaTeX style for Springer journals), 4 figures. Accepted for publication in Space Science Review

Is antimicrobial stewardship cost-effective? A narrative review of the evidence

Aims This narrative review aimed to collate recent evidence on the cost-effectiveness and cost–benefit of antimicrobial stewardship (AMS) programmes, to address the question ‘is AMS cost-effective?’, while providing resources and guidance for future research in this area. Sources PubMed was searched for studies assessing the cost-effectiveness, cost–utility or cost–benefit of AMS interventions in humans, published from January 2000 to March 2017, with no setting inclusion/exclusion criteria specified. Reference lists of retrieved reviews were searched for additional articles. Content Recent evidence on the cost-effectiveness and cost–benefit of AMS is described, studies suggest persuasive and structural AMS interventions may provide health economic benefits to the hospital setting. However, overall, cost-effectiveness evidence for AMS is severely limited, especially for the community setting. Recommendations for future research in this area are therefore provided, including discussion of appropriate health economic methodological choice. Implications Health systems have a finite and decreasing resource, decision makers currently do not have necessary evidence to assess whether AMS programmes provide sufficient benefits. Although the evidence-base of the cost-effectiveness of AMS is increasing, it remains inadequate for investment decision-making. Robust health economics research needs to be completed to enhance the generalizability and usability of cost-effectiveness results

Epidemiology and health-economic burden of urinary-catheter-associated infection in English NHS hospitals: a probabilistic modelling study

Crown Copyright © 2019 Published by Elsevier Ltd on behalf of The Healthcare Infection Society. This is an open access article under the Open Government License (OGL) (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/).International audienceBackgroundCatheter-associated urinary tract infection (CAUTI) and bloodstream infection (CABSI) are leading causes of healthcare-associated infection in England's National Health Service (NHS), but health-economic evidence to inform investment in prevention is lacking.AimsTo quantify the health-economic burden and value of prevention of urinary-catheter-associated infection among adult inpatients admitted to NHS trusts in 2016/17.MethodsA decision-analytic model was developed to estimate the annual prevalence of CAUTI and CABSI, and their associated excess health burdens [quality-adjusted life-years (QALYs)] and economic costs (£ 2017). Patient-level datasets and literature were synthesized to estimate population structure, model parameters and associated uncertainty. Health and economic benefits of catheter prevention were estimated. Scenario and probabilistic sensitivity analyses were conducted.FindingsThe model estimated 52,085 [95% uncertainty interval (UI) 42,967–61,360] CAUTIs and 7529 (UI 6857–8622) CABSIs, of which 38,084 (UI 30,236–46,541) and 2524 (UI 2319–2956) were hospital-onset infections, respectively. Catheter-associated infections incurred 45,717 (UI 18,115–74,662) excess bed-days, 1467 (UI 1337–1707) deaths and 10,471 (UI 4783–13,499) lost QALYs. Total direct hospital costs were estimated at £54.4M (UI £37.3–77.8M), with an additional £209.4M (UI £95.7–270.0M) in economic value of QALYs lost assuming a willingness-to-pay threshold of £20,000/QALY. Respectively, CABSI accounted for 47% (UI 32–67%) and 97% (UI 93–98%) of direct costs and QALYs lost. Every catheter prevented could save £30 (UI £20–44) in direct hospital costs and £112 (UI £52–146) in QALY value.ConclusionsHospital catheter prevention is poised to reap substantial health-economic gains, but community-oriented interventions are needed to target the large burden imposed by community-onset infection