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To investigate a Middle East respiratory syndrome coronavirus (MERS-CoV) outbreak event involving multiple healthcare facilities in Riyadh, Saudi Arabia; to characterize transmission; and to explore infection control implications.
Cases presented in 4 healthcare facilities in Riyadh, Saudi Arabia: a tertiary-care hospital, a specialty pulmonary hospital, an outpatient clinic, and an outpatient dialysis unit.
Contact tracing and testing were performed following reports of cases at 2 hospitals. Laboratory results were confirmed by real-time reverse transcription polymerase chain reaction (rRT-PCR) and/or genome sequencing. We assessed exposures and determined seropositivity among available healthcare personnel (HCP) cases and HCP contacts of cases.
In total, 48 cases were identified, involving patients, HCP, and family members across 2 hospitals, an outpatient clinic, and a dialysis clinic. At each hospital, transmission was linked to a unique index case. Moreover, 4 cases were associated with superspreading events (any interaction where a case patient transmitted to ≥5 subsequent case patients). All 4 of these patients were severely ill, were initially not recognized as MERS-CoV cases, and subsequently died. Genomic sequences clustered separately, suggesting 2 distinct outbreaks. Overall, 4 (24%) of 17 HCP cases and 3 (3%) of 114 HCP contacts of cases were seropositive.
We describe 2 distinct healthcare-associated outbreaks, each initiated by a unique index case and characterized by multiple superspreading events. Delays in recognition and in subsequent implementation of control measures contributed to secondary transmission. Prompt contact tracing, repeated testing, HCP furloughing, and implementation of recommended transmission-based precautions for suspected cases ultimately halted transmission.
Chronic suppurative otitis media is a massive public health problem in numerous low- and middle-income countries. Unfortunately, few low- and middle-income countries can offer surgical therapy.
A six-month long programme in Cambodia focused on training local surgeons in type I tympanoplasty was instigated. Qualitative educational and quantitative surgical outcomes were evaluated in the 12 months following programme completion. A four-month long training programme in mastoidectomy and homograft ossiculoplasty was subsequently implemented, and the preliminary surgical and educational outcomes were reported.
A total of 124 patients underwent tympanoplasty by the locally trained surgeons. Tympanic membrane closure at six weeks post-operation was 88.5 per cent. Pure tone audiometry at three months showed that 80.9 per cent of patients had improved hearing, with a mean gain of 17.1 dB. The trained surgeons reported high confidence in performing tympanoplasty. Early outcomes suggest the local surgeons can perform mastoidectomy and ossiculoplasty as safely as overseas-trained surgeons, with reported surgeon confidence reflecting these positive outcomes.
The training programme has demonstrated success, as measured by surgeon confidence and operative outcomes. This approach can be emulated in other settings to help combat the global burden of chronic suppurative otitis media.
Although social harmony is one of the most important cultural values in many of Asian societies it has rarely been studied in the mainstream management literatures. Based on the group-value theory of justice we examined how group justice climates influence group effectiveness through group harmony. Analyses of data on 106 upper-level management teams from Chinese organizations showed that justice climates were positively associated with group harmony, which in turn was positively associated with team task performance and team helping behavior. Group harmony was found to significantly mediate the positive effect of both distributive and interactional justice climates on team helping behavior but only marginally on team task performance. Finally, in support of past research both at the group and individual level, procedural justice climate had the weakest effect on group processes and outcomes. By applying the group value theory on group harmony this paper aims to integrate Eastern and Western perspectives on one hand and the justice climates and group harmony research on the other. Theoretical and practical implications are discussed.
Water cultures were significantly more sensitive than concurrently collected swab cultures (n=2,147 each) in detecting Legionella pneumophila within a Veterans Affairs healthcare system. Sensitivity for water versus swab cultures was 90% versus 30% overall, 83% versus 48% during a nosocomial Legionnaires’ disease outbreak, and 93% versus 22% post outbreak.
Africa is experiencing a rapid increase in adult obesity and associated cardiometabolic diseases (CMDs). The H3Africa AWI-Gen Collaborative Centre was established to examine genomic and environmental factors that influence body composition, body fat distribution and CMD risk, with the aim to provide insights towards effective treatment and intervention strategies. It provides a research platform of over 10 500 participants, 40–60 years old, from Burkina Faso, Ghana, Kenya and South Africa. Following a process that involved community engagement, training of project staff and participant informed consent, participants were administered detailed questionnaires, anthropometric measurements were taken and biospecimens collected. This generated a wealth of demographic, health history, environmental, behavioural and biomarker data. The H3Africa SNP array will be used for genome-wide association studies. AWI-Gen is building capacity to perform large epidemiological, genomic and epigenomic studies across several African counties and strives to become a valuable resource for research collaborations in Africa.
Massive stars are some of the most important objects in the Universe, shaping the evolution of galaxies, creating chemical elements, and hence shaping the evolution of the Universe. However, the processes by which they form, and how they shape their environment during their birth processes, are not well understood. We are using NH3 data from the “The H2O Southern Galactic Plane Survey” (HOPS) to define the positions of dense cores/clumps of gas in the southern Galactic plane that are likely to form stars. We did a comparative study with different methods for finding clumps and found Fellwalker to be the best for this dataset. We detected ~ 500 clumps with mean kinetic temperature ~ 20 K and virial mass ~ 680 solar masses.
This paper demonstrates the application of an integrated rotorcraft multidisciplinary design and optimisation framework, deployed for the purpose of preliminary design and assessment of optimum regenerative powerplant configurations for rotorcraft applications. The proposed approach comprises a wide-range of individual modelling theories applicable to rotorcraft flight dynamics, gas turbine engine performance and weight estimation as well as a physics-based stirred reactor model, for the rapid estimation of various gas turbine gaseous emissions. A single-objective Particle Swarm Optimiser is coupled with the aforementioned rotorcraft design framework. The overall methodology is deployed for the design and optimisation of a reference multipurpose Twin-Engine-Light civil rotorcraft, modelled after the Bo105 helicopter, which employs two Rolls-Royce Allison 250-C20B turboshaft engines. Through the implementation of a single-objective optimisation strategy, notionally based optimum engine design configurations are acquired in terms of engine weight, mission fuel burn and mission gaseous emissions inventory at constant technology level.
The acquired optimum regenerative engine configurations are subsequently deployed for the design of conceptual rotorcraft regenerative engine configurations, targeting improved mission fuel economy, enhanced payload-range capability as well as overall environmental impact, while maintaining the respective rotorcraft airworthiness requirements. The proposed methodology essentially constitutes as an enabler for designing rotorcraft powerplants within realistic, three-dimensional operations and towards realising their associated design trade-offs at mission level.
This work describes the time-dependent flow of an incompressible third grade fluid filling the porous half space over an infinite porous plate. The flow is induced due to the motion of the porous plate in its own plane with an arbitrary velocity V(t). Translational type symmetries are employed to perform the travelling wave reduction into an ordinary differential equation of the governing nonlinear partial differential equation which arises from the laws of mass and momentum. The reduced ordinary differential equation is solved exactly, for a particular case, as well as by using the homotopy analysis method (HAM). The better solution from the physical point of view is argued to be the HAM solution. The essentials features of the various emerging parameters of the flow problem are presented and discussed.
Commercially available bulk silicon carbide (SiC) has a high number (>2000/cm2) of screw dislocations (SD) that have been linked to degradation of high-field power device electrical performance properties. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce significantly higher quality bulk SiC. In order for this bulk growth method to become reality, growth of long single crystal SiC fibers must first be achieved. Therefore, a new growth method, Solvent-Laser Heated Floating Zone (Solvent-LHFZ), has been implemented. While some of the initial Solvent-LHFZ results have recently been reported, this paper focuses on further characterization of grown crystals and their growth fronts. To this end, secondary ion mass spectroscopy (SIMS) depth profiles, cross section analysis by focused ion beam (FIB) milling and mechanical polishing, and orientation and structural characterization by X-ray transmission Laue diffraction patterns and X-ray topography were used. Results paint a picture of a chaotic growth front, with Fe incorporation dependant on C concentration.
Bismuth vanadate (BiVO4) thin films are deposited by a low-cost and scalable spray pyrolysis method. Its performance under AM1.5 illumination is mainly limited by slow water oxidation kinetics. We confirm that cobalt phosphate (Co-Pi) is an efficient water oxidation catalyst for BiVO4. The optimum thickness of BiVO4 is 300 nm, resulting in an AM1.5 photocurrent of 1.9 mA/cm2 at 1.23 V vs. RHE when catalyzed with Co-Pi. Once the water oxidation limitation is removed, the performance is limited by low charge separation efficiency. This causes more than 60% of the electron-hole pairs to recombine before reaching the respective interfaces. The slow electron transport is shown to be the main cause of this low efficiency, and future efforts should therefore be focused on addressing this key limitation.
A new technique for improving the recovery time of bipolar power devices by misfit dislocations to fast switching speed levels is described. Misfit dislocations formed in situ at abrupt SiGe/Si heteroepitaxial interfaces are used as recombination centers in the space charge regions of devices. The density of misfit dislocations was varied over a wide range by controlling the Ge concentration and the number of Ge-containing layers in both <111> and <100> orientations. The structural properties of misfit dislocations were studied by optical microscopy, TEM, and X-ray topography. Power rectifier recovery and electrical parameters, DLTS, and minority carrier lifetime were employed to evaluate the electrical behavior of dislocations with and without gold diffusion. Fast recovery times with low leakage current and forward voltage drop were achieved by the introduction of misfit dislocations. Monotonically decreasing recovery times were obtained with increasing dislocation density. For the same recovery time, introduction of misfit dislocations produced about 50% reduction in high-temperature leakage current and similar forward voltage drop compared to devices subjected to Au diffusion. The combination of dislocations and metal impurities is also investigated and found to provide an excellent mechanism for further tailoring of the recovery characteristics of power devices. In this application the metals were preferentially accumulated in the depletion region at the misfit dislocations from small background metal concentrations leading to additional reduction of recovery time, while maintaining small leakage current and forward voltage drop.
A new experimental approach has been developed which allows characterization of rotational dynamics of NLO chromophores in amorphous polymers over 12 decades in time, from 10-6 to 106 sec. Measurements over such a broad distribution in relaxation times are important not only in determining how the chromophore orientational dynamics are coupled to polymer dynamics but also in making accurate predictions of the temporal stability of technological interest. In particular, accurate characterization over a broad range of time scales reveals that NLO polymers meet technological requirements more easily than is predicted using a less complete characterization.