This study investigates the interactions between combustor and isolator and the role played by combustion on choking-induced unstart. Shock train unsteadiness and pressure fluctuations in non-reacting environments have been previously explained in terms of shock-boundary layer interaction and acoustic forcing but, when applied to scramjets, it is still unclear whether and how this picture is altered by combustion effects. The novel experimental set-up used in this study consists of a circular cross-section model scramjet, with optically accessible combustor and isolator, tested in a high-enthalpy hypersonic free stream at Mach 4.5. A comparison is made between cases in which flow choking is induced via thermal (combustion) and non-thermal (mass addition) mechanisms using time-resolved static wall pressure measurements, high-speed flow visualization and planar laser-induced fluorescence of the OH radical as diagnostic tools. Further details on the nature of the interactions observed were provided by experiments performed in a low-enthalpy $\textrm {CO}_2$ free stream at Mach 4 using planar laser scattering visualization. The results revealed remarkable qualitative similarities between unstart processes occurring at high and low enthalpy. At high enthalpy the similarities between thermal and non-thermal choking-induced unstart were both qualitative and quantitative, suggesting very limited effect of combustion on the dynamics of the isolator shock train. Isolator flow unsteadiness, on the other hand, drastically affected the propagation of the pseudo-normal shock in the combustor, but no significant feedback effect on the isolator behaviour was observed.

We present a case of late symptom onset of COVID-19 infection 72 days after initial diagnosis in an immunocompromised 53-year-old man. SARS-CoV-2 was cultured from his sputum sample at this time, and genomic sequencing suggested reinfection was unlikely. After receipt of convalescent plasma, SARS-CoV-2 became undetectable by PCR 111 days after diagnosis, although SARS-CoV-2 antibodies remained not detectable. This case posed difficult public health management issues in a low prevalence COVID-19 setting as the person required extended home isolation given his prolonged SARS-CoV-2 PCR detection.

Subglacial hydrological systems require innovative technological solutions to access and observe. Wireless sensor platforms can be used to collect and return data, but their performance in deep and fast-moving ice requires quantification. We report experimental results from Cryoegg: a spherical probe that can be deployed into a borehole or moulin and transit through the subglacial hydrological system. The probe measures temperature, pressure and electrical conductivity in situ and returns all data wirelessly via a radio link. We demonstrate Cryoegg's utility in studying englacial channels and moulins, including in situ salt dilution gauging. Cryoegg uses VHF radio to transmit data to a surface receiving array. We demonstrate transmission through up to 1.3 km of cold ice – a significant improvement on the previous design. The wireless transmission uses Wireless M-Bus on 169 MHz; we present a simple radio link budget model for its performance in cold ice and experimentally confirm its validity. Cryoegg has also been tested successfully in temperate ice. The battery capacity should allow measurements to be made every 2 h for more than a year. Future iterations of the radio system will enable Cryoegg to transmit data through up to 2.5 km of ice.

In this paper, we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers $31\,\textrm{deg}^{2}$ at $800\,\textrm{MHz}$. As a two-dimensional array of 36$\times$12 m antennas, with baselines ranging from 22 m to 6 km, ASKAP also has excellent snapshot imaging capability and 10 arcsec resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 and $1800\,\textrm{MHz}$ and is expected to facilitate great advances in our understanding of galaxy formation, cosmology, and radio transients while opening new parameter space for discovery of the unknown.

With the legalization of marijuana (Cannabis sativa) and increasing use during pregnancy, it is important to understand its impact on exposed offspring. Specifically, the effects of Δ-9-tetrahydrocannabinol (Δ9-THC), the major psychoactive component of cannabis, on fetal ovarian development and long-term reproductive health are not fully understood. The aim of this study was to assess the effect of prenatal exposure to Δ9-THC on ovarian health in adult rat offspring. At 6 months of age, Δ9-THC-exposed offspring had accelerated folliculogenesis with apparent follicular development arrest, but no persistent effects on circulating steroid levels. Ovaries from Δ9-THC-exposed offspring had reduced blood vessel density in association with decreased expression of the pro-angiogenic factor VEGF and its receptor VEGFR-2, as well as an increase in the anti-angiogenic factor thrombospondin 1 (TSP-1). Collectively, these data suggest that exposure to Δ9-THC during pregnancy alters follicular dynamics during postnatal life, which may have long-lasting detrimental effects on female reproductive health.

Firearm injuries are a significant public health problem. Prior studies have analyzed firearm death data or adult firearm injury data, but few studies have analyzed firearm injury data specifically among youth. To inform the current debate surrounding gun policy in the United States, this study aims to provide an estimate of the immense burden of youth firearm injury and its associated risk factors. Therefore, we performed a descriptive analysis of the Nationwide Emergency Department Sample (NEDS), the largest all-payer emergency department database in the United States, from January 2006 to September 2015. All patients age < 21 who presented with any diagnosis of firearm-related injuries were included.

There were an estimated 198,839 incidents of firearm-related emergency department visits for patients age < 21 from 2006 through 2015. After presenting to the ED, an estimated 11,909 cases resulted in death. The population adjusted rate of firearm-related emergency department visits was highest in the South and Midwest. This study demonstrates the significant burden of firearm injury among youth. Having a reliable estimate of the number of children harmed by firearms each year is a critical tool for policymakers — and may make common-sense gun safety measures more politically possible.

The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be conducted with the full 36-antenna Australian Square Kilometre Array Pathfinder (ASKAP) telescope. RACS will provide a shallow model of the ASKAP sky that will aid the calibration of future deep ASKAP surveys. RACS will cover the whole sky visible from the ASKAP site in Western Australia and will cover the full ASKAP band of 700–1800 MHz. The RACS images are generally deeper than the existing NRAO VLA Sky Survey and Sydney University Molonglo Sky Survey radio surveys and have better spatial resolution. All RACS survey products will be public, including radio images (with $\sim$ 15 arcsec resolution) and catalogues of about three million source components with spectral index and polarisation information. In this paper, we present a description of the RACS survey and the first data release of 903 images covering the sky south of declination $+41^\circ$ made over a 288-MHz band centred at 887.5 MHz.

During the COVID-19 pandemic, the Division of Neurology at BC Children’s Hospital rapidly transitioned to almost exclusively virtual health. In April 2020, 96% of outpatient visits were done virtually (64%) or by telephone, and only 4.2% were in-person. Total clinic visit numbers were unchanged compared to previous months. Neurologists reported high satisfaction with the virtual history and overall assessment, while the physical examination was less reliable. Additional in-person visits were rarely required. Rapid, sustained adoption of virtual health is possible in a pediatric neurology setting, providing reliable care that is comparable to in-person consultations when physical distancing is necessary.

Background: Carbapenem-resistant Enterobacteriaceae (CRE) are endemic in the Chicago region. We assessed the regional impact of a CRE control intervention targeting high-prevalence facilities; that is, long-term acute-care hospitals (LTACHs) and ventilator-capable skilled nursing facilities (vSNFs). Methods: In July 2017, an academic–public health partnership launched a regional CRE prevention bundle: (1) identifying patient CRE status by querying Illinois’ XDRO registry and periodic point-prevalence surveys reported to public health, (2) cohorting or private rooms with contact precautions for CRE patients, (3) combining hand hygiene adherence, monitoring with general infection control education, and guidance by project coordinators and public health, and (4) daily chlorhexidine gluconate (CHG) bathing. Informed by epidemiology and modeling, we targeted LTACHs and vSNFs in a 13-mile radius from the coordinating center. Illinois mandates CRE reporting to the XDRO registry, which can also be manually queried or generate automated alerts to facilitate interfacility communication. The regional intervention promoted increased automation of alerts to hospitals. The prespecified primary outcome was incident clinical CRE culture reported to the XDRO registry in Cook County by month, analyzed by segmented regression modeling. A secondary outcome was colonization prevalence measured by serial point-prevalence surveys for carbapenemase-producing organism colonization in LTACHs and vSNFs. Results: All eligible LTACHs (n = 6) and vSNFs (n = 9) participated in the intervention. One vSNF declined CHG bathing. vSNFs that implemented CHG bathing typically bathed residents 2–3 times per week instead of daily. Overall, there were significant gaps in infection control practices, especially in vSNFs. Also, 75 Illinois hospitals adopted automated alerts (56 during the intervention period). Mean CRE incidence in Cook County decreased from 59.0 cases per month during baseline to 40.6 cases per month during intervention (P < .001). In a segmented regression model, there was an average reduction of 10.56 cases per month during the 24-month intervention period (P = .02) (Fig. 1), and an estimated 253 incident CRE cases were averted. Mean CRE incidence also decreased among the stratum of vSNF/LTACH intervention facilities (P = .03). However, evidence of ongoing CRE transmission, particularly in vSNFs, persisted, and CRE colonization prevalence remained high at intervention facilities (Table 1). Conclusions: A resource-intensive public health regional CRE intervention was implemented that included enhanced interfacility communication and targeted infection prevention. There was a significant decline in incident CRE clinical cases in Cook County, despite high persistent CRE colonization prevalence in intervention facilities. vSNFs, where understaffing or underresourcing were common and lengths of stay range from months to years, had a major prevalence challenge, underscoring the need for aggressive infection control improvements in these facilities.

Funding: The Centers for Disease Control and Prevention (SHEPheRD Contract No. 200-2011-42037)

Disclosures: M.Y.L. has received research support in the form of contributed product from OpGen and Sage Products (now part of Stryker Corporation), and has received an investigator-initiated grant from CareFusion Foundation (now part of BD).

A fibre withdrawn from a bath of a dilute particulate suspension exhibits different coating regimes depending on the physical properties of the fluid, the withdrawal speed, the particle sizes and the radius of the fibre. Our experiments indicate that only the liquid without particles is entrained for thin coating films. Beyond a threshold capillary number, the fibre is coated by a liquid film with entrained particles. We systematically characterize the role of the capillary number, the particle size and the fibre radius on the threshold speed for particle entrainment. We discuss the boundary between these two regimes and show that the thickness of the liquid film at the stagnation point controls the entrainment process. The radius of the fibre provides a new degree of control in capillary filtering, allowing greater control over the size of the particles entrained in the film.

As progress to eliminate trachoma is made, addressing hard-to-reach communities becomes of greater significance. Areas in Tanzania, inhabited by the Maasai, remain endemic for trachoma. This study assessed the effectiveness of Mass Drug Administration (MDA) through an ethnographic study of trachoma amongst a Maasai community. The MDA experience in the context of the livelihoods of the Maasai in a changing political economy was explored using participant observation and household interviews. Factors influencing MDA effectiveness within five domains were analysed. 1) Terrain of intervention: Human movement hindered MDA, including seasonal migration, domestic chores, grazing and school. Encounters with wildlife were significant. 2) Socio-cultural factors and community agency: Norms around pregnancy led women to accept the drug but hide refusal to swallow the drug. Timing of Community Drug Distributor (CDD) visits conflicted with livestock grazing. Refusals occurred among the ilmurrani age group and older women. Mistrust significantly hindered uptake of drugs. 3) Strategies and motivation of drug distributors: Maa-speaking CDDs were critical to effective drug delivery. Maasai CDDs, whilst motivated, faced challenges of distances, encounters with wildlife and compensation. 4) Socio-materiality of technology: Decreases in side-effects over years have improved trust in the drug. Restrictions to swallowing drugs and/or water were relevant to post-partum women and the ilmurrani. 5) History and health governance: Whilst perceptions of the programme were positive, communities questioned government priorities for resources for hospitals, medicines, clean water and roads. They complained of a lack of information and involvement of community members in health care services. With elimination in sight, hard-to-reach communities are paramount as these are probably the last foci of infection. Effective delivery of MDA programmes in such communities requires a critical understanding of community experiences and responses that can inform tailored approaches to trachoma control. Application of a critical social science perspective should be embedded in planning and evaluation of all NTD programmes.

A study of low-speed streaks (LSSs) embedded in the near-wall region of a turbulent boundary layer is performed using selective visualization and analysis of time-resolved tomographic particle image velocimetry (tomo-PIV). First, a three-dimensional velocity field database is acquired using time-resolved tomo-PIV for an early turbulent boundary layer. Second, detailed time-line flow patterns are obtained from the low-order reconstructed database using ‘tomographic visualizations’ by Lagrangian tracking. These time-line patterns compare remarkably well with previously observed patterns using hydrogen bubble flow visualization, and allow local identification of LSSs within the database. Third, the flow behaviour in proximity to selected LSSs is examined at varying wall distances ( $10 < y^+ < 100$ ) and assessed using time-line and material surface evolution, to reveal the flow structure and evolution of a streak, and the flow structure evolving from streak development. It is observed that three-dimensional wave behaviour of the detected LSSs appears to develop into associated near-wall vortex flow structures, in a process somewhat similar to transitional boundary layer behaviour. Fourth, the presence of Lagrangian coherent structures is assessed in proximity to the LSSs using a Lagrangian-averaged vorticity deviation process. It is observed that quasi-streamwise vortices, adjacent to the sides of the streak-associated three-dimensional wave, precipitate an interaction with the streak. Finally, a hypothesis based on the behaviour of soliton-like coherent structures is made which explains the process of LSS formation, bursting behaviour and the generation of hairpin vortices. Comparison with other models is also discussed.