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An experimental investigation was carried out in a low-turbulence wind tunnel to study the early development of artificially initiated turbulent spots in a laminar boundary layer over a flat plate. The reproducibility of the experiments allowed us to observe fine structural details that have not been observed previously. Initial velocity disturbances quickly developed into hairpin-like structures that multiplied downstream, which increased the width, length and height of the incipient turbulent spots. Only those disturbances that were greater than a threshold value developed into turbulent spots while the others decayed. The rate of development was also affected by the duration of the initial disturbances. We found that the behaviour of turbulence generation within a turbulent spot is similar to the burst events in the turbulent boundary layer, where ejection events are followed by sweep events.
Coronavirus disease 2019 has demanded enormous adjustments to National Health Service provisions. Non-urgent out-patient work was initially postponed or performed virtually, but is now being re-established. In ENT surgery, aerosol-generating procedures pose a particular challenge in out-patient settings.
A rapid restructuring of ENT out-patient services is required, to safely accommodate aerosol-generating procedures and increase in-person attendances, whilst coronavirus disease 2019 persists.
Data were collected prospectively over four consecutive cycles. Two surveys were conducted. Results were analysed and disseminated, with recommendations for service restructuring implemented at cycle end-points.
Out-patient activity increased four-fold, associated with a significant rise in aerosol-generating procedures during the study period. Mean aerosol-generating procedure duration dropped weekly, implying a learning curve. Service restructuring occurred at cycle end-points.
Iterative data gathering, results analysis and outcome dissemination enabled a swift, data-driven approach to the restructuring of ENT out-patient services. Patient and staff safety was ensured, whilst out-patient capacity was optimised.
A primary barrier to translation of clinical research discoveries into care delivery and population health is the lack of sustainable infrastructure bringing researchers, policymakers, practitioners, and communities together to reduce silos in knowledge and action. As National Institutes of Healthʼs (NIH) mechanism to advance translational research, Clinical and Translational Science Award (CTSA) awardees are uniquely positioned to bridge this gap. Delivering on this promise requires sustained collaboration and alignment between research institutions and public health and healthcare programs and services. We describe the collaboration of seven CTSA hubs with city, county, and state healthcare and public health organizations striving to realize this vision together. Partnership representatives convened monthly to identify key components, common and unique themes, and barriers in academic–public collaborations. All partnerships aligned the activities of the CTSA programs with the needs of the city/county/state partners, by sharing resources, responding to real-time policy questions and training needs, promoting best practices, and advancing community-engaged research, and dissemination and implementation science to narrow the knowledge-to-practice gap. Barriers included competing priorities, differing timelines, bureaucratic hurdles, and unstable funding. Academic–public health/health system partnerships represent a unique and underutilized model with potential to enhance community and population health.
Two new species of Oreocharis, O. tribracteata and O. rufescens, are described and a key to the species in Vietnam is provided. The new species have distinct features not previously, or rarely, observed in the genus, both showing the partial fusion of the calyx lobes into a tube, and the presence of three bracts in Oreocharis tribracteata.
This work is motivated by the need for low-order aerodynamic models to predict accurately the effect on profile drag of controlling attachment line transition. Head's entrainment method(1), a rapid integral boundary layer technique used for design studies on swept wings, suffers from the governing swept-tapered turbulent integral boundary layer equations being ill-posed in the vicinity of the attachment line. This singularity has been treated using crude extrapolations of the attachment-line similarity solution for over half a century, but this approach is unlikely to deliver accurate predictions of the effect of changes in the attachment line flow on profile drag. An experimental study has been carried out to explore the nature of the turbulent flow in the vicinity of a highly swept swept attachment line and has revealed a quite complex, non-monotonic development of the momentum thickness in this region. It has also revealed lower levels of twist in the boundary layer velocity profiles than anticipated from the highly curved character of the inviscid flow streamlines. These observations have prompted an alternative approach to the modelling of the flow in this region which not only successfully eliminates the lack of robustness in the swept-tapered equations but which also matches the experimental results to within ±5%.
The aim of this study was to retrospectively assess the value of whole genome sequencing (WGS) compared to conventional typing methods in the investigation and control of an outbreak of Shigella sonnei in the Orthodox Jewish (OJ) community in the UK. The genome sequence analysis showed that the strains implicated in the outbreak formed three phylogenetically distinct clusters. One cluster represented cases associated with recent exposure to a single strain, whereas the other two clusters represented related but distinct strains of S. sonnei circulating in the OJ community across the UK. The WGS data challenged the conclusions drawn during the initial outbreak investigation and allowed cases of dysentery to be implicated or ruled out of the outbreak that were previously misclassified. This study showed that the resolution achieved using WGS would have clearly defined the outbreak, thus facilitating the promotion of infection control measures within local schools and the dissemination of a stronger public health message to the community.
The European badger (Meles meles) has been identified as a wildlife reservoir of bovine tuberculosis and a source of transmission to cattle in Britain and Ireland. Both behavioural ecology and statistical ecological modelling have indicated the long-term persistence of the disease in some badger communities, and this is postulated to account for the high incidence of bovine tuberculosis in cattle across large tracts of England and Wales. This paper questions this consensus by using historical cartographic evidence to show that tuberculosis in cattle had a very different spatial distribution before 1960 to the present day. Since few of the badgers collected in road traffic accidents between 1972 and 1990 had tuberculosis in counties such as Cheshire, where the disease had until shortly before that been rife in the cattle population, the role of badgers as reservoirs in spreading disease in similar counties outside the south-west of England has to be questioned.
A recently discovered synthetic route to new kinetically stable [(MSe)y]m[TSe2]n layered intergrowths has been applied to prepare several different compositions (M = Pb or Sn, T = Ta, Nb, Mo, or W) with m = n = 1, in thin film form. Scanning transmission electron microscopy and synchrotron X-ray diffraction show the nanostructure of these materials is characterized by a combination of in-plane component crystallinity with misregistration and rotational mis-orientation between adjacent layers. Extremely low cross-plane thermal conductivity as low as 0.1 W m-1 K-1 are attributed to the turbostratic nanostructure. By appropriate choice of M and T, we demonstrate that a range of electrical transport properties are possible, from metallic to semiconducting. Annealing (PbSe)0.99WSe2 and (PbSe)1.00MoSe2 specimens in a controlled atmosphere of PbSe or WSe2 is observed to systematically influence carrier properties, and is interpreted in terms of reduction of the concentration of electrically active defects. Considering these observations and the large composition and structural space that can be explored in such [(MSe)y]m[TSe2]n intergrowths, these materials are of interest for further investigation as potential thermoelectric materials.
In November and December 1992, an outbreak of parvovirus B19 infection occurred among patients and staff on an adult mixed surgical ward at a large hospital in London. Three patients and 15 staff members were serologically confirmed as acute cases. The attack rate among susceptible members of staff was 47%. In those infected, arthralgia (80%) and rash (67%) were the most common symptoms. Of six susceptible in-patients on the ward, three became infected. One of the in-patients who had carcinoma of the mouth was viraemic for more than 10 days with marrow suppression resulting in the postponement of chemotherapy until intravenous immunoglobulin was given and he was no longer viraemic. Control measures taken included closure of the ward to new admissions, transfer of only immune staff to the ward, and restriction of the ward nursing staff to working only on that ward. Although no specific exposure was conclusively identified as a risk factor, there was a suggestion of an increased risk of acquiring parvovirus B19 infection among those staff who did not adopt strict hand washing procedures after each physical contact with a patient (RR = 2·33; P = 0·07). Knowledge of parvovirus B19 among interviewed health care workers was poor: only 42% reported knowing about parvovirus B19 and only 38% could name a patient category at risk of a severe outcome following infection. This is the first report of a nosocomial outbreak affecting an adult ward and of possible transmission of parvovirus B19 infection from staff to in-patients. Hospital control of infection teams should include parvovirus B19 in their outbreak containment plans.
There has been growing public concern with regard to the effects of heavy metals excreted by animals on the environment. Heavy metals can be lost from manure and slurry to ground and surface waters, and subsequently affect water quality (Van Horn et al., 1996). In regions of high domestic livestock production, farmers are therefore seeking means to reduce the quantity of heavy metals excreted by animals and subsequently onto the land (Van Horn et al., 1996). The objective of this study was to establish the effect of two levels of dietary Zn inclusion in two different forms (organically chelated vs. inorganic) on apparent absorption and retention in dairy cattle.
It is well established that zinc is an essential micro-nutrient required to maintain health and performance in dairy cows (Underwood and Suttle, 2004). Cattle diets are traditionally supplemented with inorganic minerals (e.g. zinc oxide), but these may be poorly absorbed, resulting in an economic and environmental cost due to excess minerals being excreted. It is claimed organically bound minerals are able to resist interaction before and at the absorption site in the small intestine (Power, 2006), which may result in a lower dietary inclusion rate being required. The objective of the current experiment was to investigate the effect of an organically bound source of Zn as a replacement for inorganic Zn on dairy cow health and performance when supplemented at and below the recommended level.
Microtubules (MT) are dynamic protein-based polymers with numerous applications in materials science including the active transport of nanomaterials and as templates for biomimetic materials synthesis. Some of these applications require that the dynamic nature of the MT be suppressed, and in this report we will discuss the preparation and stability of chemically crosslinked microtubules (CLMTs). MT reaction with gluteraldehyde results in the formation of protein dimers and higher molecular weight oligimers as observed by gel electrophoresis, confirming the formation of covalent inter-protein linkages. While extensive crosslinking was found to destabilize MTs and inactivate them with regards to kinesin binding, moderate amounts of crosslinking lead to CLMTs that had functional lifetimes of at least twice that of uncrosslinked MTs. Further studies demonstrated that CLMTs exhibited a wider thermal stability window and were far more resistant to metal-ion induced depolymerization than uncrosslinked MTs.
Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. β-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.
Collections of Cyrtandra from the island of Palawan in the Philippines are reviewed. Twelve species are present, of which only five species are already described. A further three species and one variety are described here: C. cleopatrae H.J. Atkins & Cronk sp. nov., C. pulgarensis [Elmer ex] H.J. Atkins & Cronk sp. nov., C. hirtigera H.J. Atkins & Cronk sp. nov., and C. hirtigera var. chlorina H.J. Atkins & Cronk var. nov. Further material of the remaining four taxa (spp. B, C, D, E) will be needed before these can be formally named, although descriptions are provided here. All species are endemic except C. elatostemoides Elmer and C. hypochrysoides Kränzl., which also occur in Borneo and Luzon respectively. The pattern of narrow endemism shown by the cyrtandras of Palawan is commented on briefly.
In vitro runoff transcription using T7 RNA polymerase
has been the method of choice to produce milligram quantities
of RNA for structural studies. Unfortunately, the T7 enzyme
often adds one or more extra nucleotides at the 3′
end, which results in a heterogeneous RNA product (Milligan
et al., 1987). This heterogeneity can be observed at the
5′ end as well, depending on the transcription template
(Ferre-D'Amare & Doudna, 1996). The lack of homogeneity,
which potentially is deleterious for structural studies,
can be overcome with the use of cis- and/or trans-acting
ribozymes, which produce clean RNA ends after their catalytic
reaction (Ferre-D'Amare & Doudna, 1996). This
procedure has been scaled up for large quantities of RNA
for NMR and X-ray crystallographic studies, and is useful
for purification of larger RNAs (greater than 50 nt) where
single-nucleotide resolution by gel electrophoresis is
difficult. Ribozymes that have been used in this manner
include the hairpin ribozyme, the hammerhead ribozyme (HH),
the hepatitis delta ribozyme (δ), and the Neurospora
varkud satellite RNA ribozyme (VS) (Guo & Collins,
1995; Price et al., 1995; Ferre-D'Amare & Doudna,
1996). All of these ribozymes leave a 5′-hydroxyl
and a 3′-cyclic phosphate as products of cleavage.
X-ray absorption measurements are described for identifying metal impurities in
silica preforms, the rod-like starting materials from which hair-like optical fibers are drawn.
The results demonstrate the effectiveness of this approach as a non-destructive,
quantitative, element-selective, position-sensitive, and chemical-state-specific means for
characterizing transition metals in the concentration regime of parts per billion.