Aerodynamic testing and development of Sunswift eVe

The current understanding of the aerodynamic performance of Sunswift’s solar-electric race car eVe is limited, despite the design and manufacture of the vehicle in 2012-13. This paper describes an investigation into the aerodynamic behaviour of the vehicle and details the successive design and development of drag minimisation strategies. A study of the ex­ternal airflow around the vehicle was undertaken through a computational fluid dynamics analysis, with validation offered through the results of real-world track testing. Particular reference is made to the Sunswift team’s successful long-range electric vehicle land speed record attempt on 23 July 2014. A predicted 10% reduction in drag has been achieved through external bodywork modifications as described within this paper. Recommenda­tions for the design of low drag vehicles are also presented, with relation made to the future of sustainable transport

Penrose limits of homogeneous spaces

We prove that the Penrose limit of a spacetime along a homogeneous geodesic is a homogeneous plane wave spacetime and that the Penrose limit of a reductive homogeneous spacetime along a homogeneous geodesic is a Cahen--Wallach space. We then consider several homogenous examples to show that these results are indeed sharp and conclude with a remark about the existence of null homogeneous geodesics.Comment: 16 pages, many changes particularly to sections 6 and

Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed

[EN] Developments in materials, manufacturing and computing methods have catalysed the generation of efficient compressor designs with higher specific power outputs. Centrifugal compressors have become pervasive in environments demanding a combination of higher power with smaller sizes such as unmanned aerial vehicles, micro gas turbines and turbochargers. These compressors are expected to perform optimally in a range of operational speeds and mass flow states with low acoustic emissions. The impact of operating speed on the flow and acoustic characteristics of a ported shroud compressor has been explored in this work. The operation of the open and blocked configurations of the compressor at the design and near surge points each of a lower and a higher speedline was numerically and experimentally investigated. Comparing the results, the model was shown to predict the operation of the compressor for both configurations at the investigated operating points satisfactorily in terms of both performance and dominant acoustic features. With an increase in the velocity and the Mach number due to increased operational speed, changes in the flow behaviour in the inducer and diffuser were observed. An increase in operational speed was shown to generally increase the overall acoustic emission of the compressor for both configurations. The number of distinct tones in the acoustic output and their magnitude were also seen to be a function of operating speed.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The project was sponsored and supported by the BorgWarner Turbo Systems and the Regional Growth Fund (RGF Grant Award 01.09.07.01/1789C).Sharma, S.; Garcia Tiscar, J.; Allport, JM.; Barrans, S.; Nickson, AK. (2021). Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed. International Journal of Engine Research. 22(5):1592-1604. https://doi.org/10.1177/1468087420916606S1592160422

Effects of ported shroud casing treatment on the acoustic and flow behaviour of a centrifugal compressor

[EN] Centrifugal turbomachines of smaller sizes operating at higher speeds have become pervasive due to the increased specific power and reliability achieved by improvements in manufacturing, materials and computational methods. The presence of these small turbomachines, specifically compressors, in helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers and micro gas turbines necessitates superior aerodynamic performance over a broad operational range which is widely achieved by ported shroud casing designs. In addition to aerodynamic performance, acoustic emissions have become a critical aspect of design for these small centrifugal compressors due to high operational speeds. Furthermore, the literature on the acoustic effects of the casing treatment is rather limited. Therefore, the impact of ported shroud casing treatment on the acoustic and flow features of the compressor operating at the design and near surge conditions have been quantified by numerically modelling the open and blocked configuration of the compressors. Upon comparing with experimental results, the numerical spectra are shown to capture the differences between the two configurations at the investigated operating points with reasonable accuracy. Although the casing treatment is generally seen to decrease the overall acoustic emission of the compressor at both operating conditions, increased propagation of tonal content in the direction upstream to the impeller is observed, particularly for design operation. Broadband characteristics in the lower and medium frequency regions usually associated with near surge operation including `whoosh' noise are observed to be alleviated by the ported shroud casing treatment.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: The project is sponsored and supported by BorgWarner Turbo Systems and the Regional Growth Fund (RGF Grant Award 01.09.07.01/1789C).Sharma, S.; Garcia Tiscar, J.; Allport, JM.; Barrans, S.; Nickson, AK. (2020). Effects of ported shroud casing treatment on the acoustic and flow behaviour of a centrifugal compressor. International Journal of Engine Research. 21(6):998-1011. https://doi.org/10.1177/1468087419880431S998101121

Comparison and imputation-aided integration of five commercial platforms for targeted DNA methylome analysis

Targeted bisulfite sequencing (TBS) has become the method of choice for the cost-effective, targeted analysis of the human methylome at base-pair resolution. In this study, we benchmarked five commercially available TBS platforms-three hybridization capture-based (Agilent, Roche and Illumina) and two reduced-representation-based (Diagenode and NuGen)-across 11 samples. Two samples were also compared with whole-genome DNA methylation sequencing with the Illumina and Oxford Nanopore platforms. We assessed workflow complexity, on/off-target performance, coverage, accuracy and reproducibility. Although all platforms produced robust and reproducible data, major differences in the number and identity of the CpG sites covered make it difficult to compare datasets generated on different platforms. To overcome this limitation, we applied imputation and show that it improves interoperability from an average of 10.35% (0.8 million) to 97% (7.6 million) common CpG sites. Our study provides guidance on which TBS platform to use for different methylome features and offers an imputation-based harmonization solution that allows comparative, integrative analysis

Pharmacokinetics-pharmacodynamics of tazobactam in combination with cefepime in an in vitro infection model

We previously demonstrated that for tazobactam administered in combination with ceftolozane, the pharmacokinetic-pharmacodynamic (PK-PD) index that best described tazobactam efficacy was the percentage of the dosing interval that tazobactam concentrations were above a threshold (%T>threshold). Using data from studies of Enterobacteriaceae-producing ESBL, a relationship between tazobactam %T>threshold and reduction in log10 CFU from baseline, for which tazobactam threshold concentration was the product of the isolate's ceftolozane-tazobactam MIC value and 0.5, was identified. However, since the kinetics of cephalosporin hydrolysis vary among ESBLs and compounds, it is likely that the translational relationship to derive the tazobactam threshold concentration varies among enzymes and compounds. Using a one-compartment in vitro infection model, the PK-PD of tazobactam administered in combination with cefepime was characterized and a translational relationship across ESBL-producing Enterobacteriaceae was developed. Four clinical isolates, two Escherichia coli and two Klebsiella pneumoniae, known to produce CTX-M-15 β-lactamase enzymes and displaying cefepime MIC values of 2 to 4 mg/L in the presence of 4 mg/L tazobactam, were evaluated. Tazobactam threshold concentrations from 0.0625-1 times the tazobactam-potentiated cefepime MIC value were considered. The threshold that best described the relationship between tazobactam %T>threshold and change in log10 CFU from baseline was the product of 0.125 and the cefepime-tazobactam MIC (R2=0.813). The magnitude of %T>threshold associated with net bacterial stasis and a 1-log10 CFU/mL reduction from baseline at 24 hours was 21.9 and 52.8%, respectively. These data will be useful to support the identification of tazobactam dosing regimens in combination with cefepime for evaluation in future clinical studies

Global well-posedness of the 3-D full water wave problem

We consider the problem of global in time existence and uniqueness of solutions of the 3-D infinite depth full water wave problem. We show that the nature of the nonlinearity of the water wave equation is essentially of cubic and higher orders. For any initial interface that is sufficiently small in its steepness and velocity, we show that there exists a unique smooth solution of the full water wave problem for all time, and the solution decays at the rate $1/t$.Comment: 60 page

Evidence for biphasic uncoating during HIV-1 infection from a novel imaging assay

BACKGROUND: Uncoating of the HIV-1 core plays a critical role during early post-fusion stages of infection but is poorly understood. Microscopy-based assays are unable to easily distinguish between intact and partially uncoated viral cores. RESULTS: In this study, we used 5-ethynyl uridine (EU) to label viral-associated RNA during HIV production. At early time points after infection with EU-labeled virions, the viral-associated RNA was stained with an EU-specific dye and was detected by confocal microscopy together with viral proteins. We observed that detection of the viral-associated RNA was specific for EU-labeled virions, was detected only after viral fusion with target cells, and occurred after an initial opening of the core. In vitro staining of cores showed that the opening of the core allowed the small molecule dye, but not RNase A or antibodies, inside. Also, staining of the viral-associated RNA, which is co-localized with nucleocapsid, decays over time after viral infection. The decay rate of RNA staining is dependent on capsid (CA) stability, which was altered by CA mutations or a small molecule inducer of HIV-1 uncoating. While the staining of EU-labeled RNA was not affected by inhibition of reverse transcription, the kinetics of core opening of different CA mutants correlated with initiation of reverse transcription. Analysis of the E45A CA mutant suggests that initial core opening is independent of complete capsid disassembly. CONCLUSIONS: Taken together, our results establish a novel RNA accessibility-based assay that detects an early event in HIV-1 uncoating and can be used to further define this process