808 research outputs found
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Pressure shielding mechanism of canopies for trailing edge noise reduction in aerofoils
Session: Airframe / High-Lift Noise IView Video Presentation: https://doi.org/10.2514/6.2023-3204.vidThe pressure shielding mechanism of bio-inspired surface treatment, called canopies, has been investigated experimentally and applied to reduce trailing edge noise generated by aero- foils. Surface pressure experiments beneath the boundary layer on a flat and aerofoil section show that canopies can attenuate surface pressure in two frequency ranges, ∆ f 1 = 0.1 to 1.0 kHz and ∆f2 = 2 to 12 kHz, at some critical canopies’ height from the wall. Canopies with an Open-Area-Ratio (OAR or σ) of 50 % placed closer (h/δ=0.08) to the surface tend to in- crease attenuation with frequency, without any low-frequency peak attenuation. This high- frequency attenuation is mainly due to the mechanism of dissipation, of small-scale structures in the boundary-layer, provided by the canopies, which have relatively higher wall shear stress compared to flat plate or thicker canopy designs. As h/δ increases, the low-frequency atten- uation in the surface pressure becomes noticeable, with a peak value of 5 dB for a critical height of h/δ∗ ∼ 1, indicating the mechanism of blockage or shielding of large structures in the boundary-layer is responsible for the low-frequency attenuation. For h/δ ≥ 0.16, both the low- and high-frequency attenuation reduces and becomes almost zero for h/δ = 0.5. Furthermore, the mechanism of pressure shielding provided by the canopy treatment is shown to be a local phenomenon, for 70% <OAR < 90 % and very sensitive to the location of the canopy itself. The maximum attenuation in surface pressure is seen for the canopy geometries with small rod diameters with less spacing. The optimum canopy geometry, based on the surface pres- sure studies, was applied near the trailing edge of the NACA0012 aerofoil. The far-field noise study demonstrates, for the first time, that canopies can reduce broadband noise levels up to 12-14 dB in the frequency range between 2 and 12 kHz, provided they are scaled appropriately based on the incoming turbulent boundary-layer flow.EPSRC under grant No. EP/V038273/1
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Modified TNO-Blake model for aerofoil surface pressure prediction with canopies
Session: Airframe / High-Lift Noise IView Video Presentation: https://doi.org/10.2514/6.2023-3203.vidThe modelling of the surface pressure spectrum beneath a turbulent boundary layer near the trailing edge of an aerofoil with bio-inspired surface treatments, called canopies, is investigated. Canopies are simply a cylindrical rods uniformly spaced along the span of the aerofoil. The velocity measurements indicated that the flow at the trailing edge of an aerofoil treated with canopies is localised and shows periodic behaviour across the span with treatment spacing. As a result, the mean-flow velocity gradient along the span (@U1=@x3) cannot be assumed as zero for x2=h = 4, which is shown in this paper. Therefore, the original surface pressure solution of Poisson’s equation is modified by introducing an additional source term consisting of the mean-shear contribution, given as @U1=@x3 @u3=@x1. Furthermore, the surface pressure attenuation due to the canopies shows a periodic behaviour across the span for treatments with an Open-Area-Ratio (OAR) between 70% and 90 %. This observation is consistent with our previous experimental results; therefore, the primary motivation for proposing a 3D TNO-Blake model, accounting for the interaction between the gradient of the stream-wise mean velocity along the span and span-wise fluctuating component along the stream. The model is built based on the inputs from Large Eddy Simulation results and additional wind tunnel measurements.EPSRC under grant No EP/V038273/1
Human Computation and Convergence
Humans are the most effective integrators and producers of information,
directly and through the use of information-processing inventions. As these
inventions become increasingly sophisticated, the substantive role of humans in
processing information will tend toward capabilities that derive from our most
complex cognitive processes, e.g., abstraction, creativity, and applied world
knowledge. Through the advancement of human computation - methods that leverage
the respective strengths of humans and machines in distributed
information-processing systems - formerly discrete processes will combine
synergistically into increasingly integrated and complex information processing
systems. These new, collective systems will exhibit an unprecedented degree of
predictive accuracy in modeling physical and techno-social processes, and may
ultimately coalesce into a single unified predictive organism, with the
capacity to address societies most wicked problems and achieve planetary
homeostasis.Comment: Pre-publication draft of chapter. 24 pages, 3 figures; added
references to page 1 and 3, and corrected typ
Relationship between autoantibody clustering and clinical subsets in SLE: cluster and association analyses in Hong Kong Chinese
OBJECTIVE: This study aims to identify the existence of, and relationship between autoantibody clusters and clinical subsets in Chinese SLE patients. METHODS: Data from 1928 SLE patients from Hong Kong were analysed. Using cluster analysis, patients were grouped by autoantibodies into clusters. The frequencies of various clinical manifestations were then compared between each cluster. Separate association analyses between individual autoantibodies and clinical manifestations as well as between clinical manifestations were also performed without any prior clustering. RESULTS: Three separate autoantibody clusters were identified, each with significantly different clinical manifestations. Cluster 1 was characterized by anti-dsDNA and the greatest prevalence of renal disorder but the lowest frequencies of other clinical manifestations. Cluster 2 was represented by the predominance of anti-Smith, anti-RNP and aPL, with greater prevalence of malar rash, oral ulcers, arthritis and serositis. Cluster 3 was characterized by anti-Ro and anti-La with greater prevalence of discoid rash, photosensitivity and haematological involvement. Individual association analysis also revealed similar findings. Patients of clusters 2 and 3 were more closely related, while cluster 1 was more distinct, associated with renal disorder only and negatively associated or not associated with other manifestations. CONCLUSION: We conclude that autoantibody clustering and clinical subsets exist in SLE patients of our locality. These clusters may be viewed as a bipolar spectrum of related autoantibody and clinical manifestations. At one end are patients with over-representation of anti-dsDNA and renal disorder, while at the other end are two distinct autoantibody clusters (anti-Sm/anti-RNP/aPL and anti-Ro/anti-La) with overlapping of other clinical manifestations.postprin
In Search of an Uncultured Human-Associated TM7 Bacterium in the Environment
We have identified an environmental bacterium in the Candidate Division TM7 with ≥98.5% 16S rDNA gene homology to a group of TM7 bacteria associated with the human oral cavity and skin. The environmental TM7 bacterium (referred to as TM7a-like) was readily detectable in wastewater with molecular techniques over two years of sampling. We present the first images of TM7a-like cells through FISH technique and the first images of any TM7 as viable cells through the STARFISH technique. In situ quantification showed TM7 concentration in wastewater up to five times greater than in human oral sites. We speculate that upon further characterization of the physiology and genetics of the TM7a-like bacterium from environmental sources and confirmation of its genomic identity to human-associated counterparts it will serve as model organisms to better understand its role in human health. The approach proposed circumvents difficulties imposed by sampling humans, provides an alternative strategy to characterizing some diseases of unknown etiology, and renders a much needed understanding of the ecophysiological role hundreds of unique Bacteria and Archaea strains play in mixed microbial communities
Pilot Scale Production of Highly Efficacious and Stable Enterovirus 71 Vaccine Candidates
BACKGROUND: Enterovirus 71 (EV71) has caused several epidemics of hand, foot and mouth diseases (HFMD) in Asia and now is being recognized as an important neurotropic virus. Effective medications and prophylactic vaccine against EV71 infection are urgently needed. Based on the success of inactivated poliovirus vaccine, a prototype chemically inactivated EV71 vaccine candidate has been developed and currently in human phase 1 clinical trial. PRINCIPAL FINDING: In this report, we present the development of a serum-free cell-based EV71 vaccine. The optimization at each step of the manufacturing process was investigated, characterized and quantified. In the up-stream process development, different commercially available cell culture media either containing serum or serum-free was screened for cell growth and virus yield using the roller-bottle technology. VP-SFM serum-free medium was selected based on the Vero cell growth profile and EV71 virus production. After the up-stream processes (virus harvest, diafiltration and concentration), a combination of gel-filtration liquid chromatography and/or sucrose-gradient ultracentrifugation down-stream purification processes were investigated at a pilot scale of 40 liters each. Although the combination of chromatography and sucrose-gradient ultracentrifugation produced extremely pure EV71 infectious virus particles, the overall yield of vaccine was 7-10% as determined by a VP2-based quantitative ELISA. Using chromatography as the downstream purification, the virus yield was 30-43%. To retain the integrity of virus neutralization epitopes and the stability of the vaccine product, the best virus inactivation was found to be 0.025% formalin-treatment at 37 °C for 3 to 6 days. Furthermore, the formalin-inactivated virion vaccine candidate was found to be stable for >18 months at 4 °C and a microgram of viral proteins formulated with alum adjuvant could induce strong virus-neutralizing antibody responses in mice, rats, rabbits, and non-human primates. CONCLUSION: These results provide valuable information supporting the current cell-based serum-free EV71 vaccine candidate going into human Phase I clinical trials
Gene-Based Meta-Analysis of Genome-Wide Association Study Data Identifies Independent Single-Nucleotide Polymorphisms in ANXA6 as Being Associated With Systemic Lupus Erythematosus in Asian Populations
Objective Previous genome-wide association studies (GWAS), which were mainly based on single-variant analysis, have identified many systemic lupus erythematosus (SLE) susceptibility loci. However, the genetic architecture of this complex disease is far from being understood. The aim of this study was to investigate whether using a gene-based analysis may help to identify novel loci, by considering global evidence of association from a gene or a genomic region rather than focusing on evidence for individual variants. Methods Based on the results of a meta-analysis of 2 GWAS of SLE conducted in 2 Asian cohorts, we performed an in-depth gene-based analysis followed by replication in a total of 4,626 patients and 7,466 control subjects of Asian ancestry. Differential allelic expression was measured by pyrosequencing. Results More than one-half of the reported SLE susceptibility loci showed evidence of independent effects, and this finding is important for understanding the mechanisms of association and explaining disease heritability. ANXA6 was detected as a novel SLE susceptibility gene, with several single-nucleotide polymorphisms (SNPs) contributing independently to the association with disease. The risk allele of rs11960458 correlated significantly with increased expression of ANXA6 in peripheral blood mononuclear cells from heterozygous healthy control subjects. Several other associated SNPs may also regulate ANXA6 expression, according to data obtained from public databases. Higher expression of ANXA6 in patients with SLE was also reported previously. Conclusion Our study demonstrated the merit of using gene-based analysis to identify novel susceptibility loci, especially those with independent effects, and also demonstrated the widespread presence of loci with independent effects in SLE susceptibility genes. © 2015, American College of Rheumatology.postprin
The clinical features of the piriformis syndrome: a systematic review
Piriformis syndrome, sciatica caused by compression of the sciatic nerve by the piriformis muscle, has been described for over 70 years; yet, it remains controversial. The literature consists mainly of case series and narrative reviews. The objectives of the study were: first, to make the best use of existing evidence to estimate the frequencies of clinical features in patients reported to have PS; second, to identify future research questions. A systematic review was conducted of any study type that reported extractable data relevant to diagnosis. The search included all studies up to 1 March 2008 in four databases: AMED, CINAHL, Embase and Medline. Screening, data extraction and analysis were all performed independently by two reviewers. A total of 55 studies were included: 51 individual and 3 aggregated data studies, and 1 combined study. The most common features found were: buttock pain, external tenderness over the greater sciatic notch, aggravation of the pain through sitting and augmentation of the pain with manoeuvres that increase piriformis muscle tension. Future research could start with comparing the frequencies of these features in sciatica patients with and without disc herniation or spinal stenosis
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