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Abstract Detailed experimental comparisons had been conducted between calibrated and rainbow schlieren on perfectly- and under-expanded axisymmetric supersonic jets through a modified Z-type schlieren system. The techniques were implemented by using a weak lens in the field-of-view to provide calibration information for the extraction of quantitative density gradients from the experimental schlieren images. Sixth-order polynomial curve fits were obtained for both calibrated and rainbow schlieren respectively. The effects of light inhomogeneity caused by the mirrors and system diaphragm aperture had been evaluated for the colour images and results indicate that averaging the background hue is an acceptable approach for minimizing light variations with less than 2% experimental error. Density gradients as calculated via Abel transform have also been evaluated to validate the two different set-ups. Additionally, experimental results have been compared to validated numerical results and they show that calibrated schlieren is able to predict density gradients within 2% of the numerical results. This is significantly more superior to rainbow schlieren, where errors in the estimated density gradients are closer to 20%. It is shown here that rainbow schlieren results are more adversely impacted by the system diaphragm aperture, especially for vertical light cut-off configuration. This is partly due to the loss of sensitivity of the schlieren system, as well as potential light diffusion caused by the filter. Highlights • Supersonic jet density gradients determined by calibrated and rainbow schlieren. • Calibrated schlieren performs better than rainbow Schlieren in the present study. • Calibrated and rainbow schlieren lead to about 2% and 20% discrepancy respectively. • Calibrated schlieren is more sensitive, robust and captures more flow features. • Rainbow schlieren sensitivity is dependent on filter quality and light inhomogeneity. [ABSTRACT FROM AUTHOR]

This study focuses on insects and other arthropods sampled on the exhumation of an infant skeleton belonging to 'Prof. Dr. Rómulo Lambre'skeletal collection. The body was buried in soil inside a wooden coffin in a grave 40 cm deep, in autumn, and stored in the cemetery deposit after exhumation. Death records were obtained from the cemetery archive. Samples of faunal remains were recovered from wrappings, clothes, bones and soil samples, and were identified at different taxonomic levels depending on the stage of conservation. The dominant taxon was the muscid fly Ophyra aenescens (Wiedemann). The relationships among the identified taxa and the moving of the corpse, from the burial context to the cemetery deposit, are discussed and used to create a hypothetical colonization sequence after death. The application of entomological data to anthropological research can provide valuable information for the interpretation of taphonomic processes and burial contexts. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study has been conducted on the impingement of compressible vortex rings on stationary, inclined, smooth surfaces. Four surface angle inclinations were evaluated: 90° (perpendicular to the flow longitudinal axis), 75°, 60°, and 45°. The flow was assumed axisymmetric for the 90° benchmark case. A single pressure ratio of ∼4 was used, corresponding to an experimental incident shock wave Mach number of ∼1.31, generating a shock-free compressible vortex ring. Results showed two main flow processes: the interaction of the reflected shock wave with the approaching vortical structure, and the impingement of the vortex ring on the surface. At surface inclination angles other than 90°, these processes are asymmetrical and the shape of the reflected shock is modified by the approaching vortex ring. The lower outer section of the reflected shock wave is initially diffracted by the lower core of the vortex ring, its central section is then captured by the central section of the torus, and ultimately the upper outer section is diffracted by the upper core. The vortex ring subsequently impinges on the surface with the lower core impacting first, undergoing an asymmetrical stretching and deformation. Flow field studies showed an initial decrease in velocity magnitude and vorticity field as the flow transitioned from a symmetrical to an asymmetrical impingement, possibly due to the uneven formation of the boundary layer. The velocity magnitude and vorticity field of the upper core subsequently increase again, as a result of the upwards deflection of the flow. Oppositely, the lower core is seen to dissipate. Surface pressure measurements confirmed the asymmetry in the flow development. As the surface angle is varied, the pressure at the central measurement location is seen to decrease as the position of the stagnation point is altered. An interesting feature within the surface measurements is a strong lateral acceleration due to the formation of vortex lines which roll around the main vortex core. [Copyright &y& Elsevier]

Abstract: Safety is one of the key issues of future automobile development. Car maker as well as suppliers need to prove that, despite increasing complexity, their electronic systems will deliver the required functionality safely and reliably. Future development and integration of these functionalities will even strengthen the need of safe system development processes and the possibility to provide evidence that all reasonable safety objectives are satisfied. Obviously with the trend of increasing complexity, there are increasing risks from systematic failures and random hardware faults that could impact negatively on vehicle safety. Safety relevant systems (such as advanced driving assistance and vehicle dynamic control units) require microcontrollers able to guarantee safety and availability with an acceptable cost. Safety must be achieved with respect to both systematic and hardware random faults, including soft-errors and common-cause failures. To provide availability, efficient and fast fault detection mechanisms shall be combined with infrastructures able to collect error events with enough details to allow reactions by the remaining hardware and the operating system. Costs shall be minimized by introducing as much robustness as needed and not more: this shall be done by avoiding unnecessary redundancies and reducing at the minimum the impact on system performances, therefore maximizing the usage of the available resources. This paper will give a short introduction on main concept of functional safety and ISO/DIS 26262, underlining the impact of such requirements on microprocessors and microcontrollers design. Some examples will be given on current approaches used to answer ISO/DIS 26262 requirements. [Copyright &y& Elsevier]

Highlights • Novel shock structure reconstruction technique based on schlieren and visual hull. • Prior knowledge of global velocity or density field not required for reconstruction. • Achieved high resolution and 2.5% average error in reconstructed shock structures. • Successful reconstruction of axisymmetric and asymmetric shock structures. • Relative to current methods, proposed technique is fast, robust and easy to apply. Abstract Three-dimensional shock structures produced by Mach 1.45 supersonic bevelled jets were digitally reconstructed based on schlieren photography and a voxel-based visual hull technique. By taking advantage of the strong edge features commonly found in schlieren images of shock waves, the proposed technique demonstrates the possibility of performing shock wave reconstruction in supersonic jet applications without prior knowledge of the global density or velocity field. Semi-synthetic camera parameters were introduced as a method to circumvent camera calibration issues faced in the reconstruction procedure. This is key to achieving accurate and high-resolution reconstructed shock waves for both axisymmetric and asymmetric test cases with an average of 2.5% error when validated against raw schlieren images. When applied to bevelled jets with non-uniform nozzle exit geometries, an additional assumption was made to address the problem of schlieren line-of-sight blockage by the non-conventional nozzle, and reconstruction errors were found to be larger near regions of poorer shock wave contrast. Current results indicate that the technique is robust and fast during image calibration and processing, with accuracy of reconstructed shock waves in both conventional and non-conventional nozzles strongly dependent on shock wave contrast. Compared to existing techniques that can be used to reconstruct 3D shock structures, the proposed technique has the advantage of being totally non-intrusive as compared to point or particle-based measurements, requires significantly less computation than tomographic methods, offers high resolution reconstruction even with limited camera resolution and projected schlieren views, and is easy and cost effective to implement. [ABSTRACT FROM AUTHOR]

Moderately under-expanded jets issuing from a circular baseline and two bevelled circular nozzles impinging upon a perpendicular flat plate were experimentally studied. The effects of nozzle-pressure-ratio and separation distance variations on the standoff shock formations were investigated with schlieren visualizations and a visual hull based three-dimensional (3D) shock reconstruction technique to provide deeper insights into their 3D features. Across all flow configurations arising from the different combinations of these parameters, results indicated that the bevelled nozzles are effective in introducing asymmetry to the standoff shock geometries. Depending on the exact flow configuration, standoff shock locations may also undergo significant upstream displacements. In particular, the single-bevelled nozzle produces highly unsteady standoff shocks with asymmetric oscillation amplitudes along both side of the nozzle lip regions. Changes to the standoff shock key characteristics were observed to be sensitive towards the jet shock structures and reflection point modified by the bevelled nozzle exits. In particular, the strength and relative position of the reflection point are identified as the major contributing factors influencing the upstream static pressure distribution of the standoff shock, hence leading to the observed changes in the standoff shock behaviour. [ABSTRACT FROM AUTHOR]

Abstract: Dendritic cells (DCs) induce and regulate T-cell responses, and tolerogenic DCs can promote the development of regulatory T cells with suppressive activity. The possibility of manipulating DCs using different pharmacological or biological agents, enabling them to exert tolerogenic activities, could be exploited to better control a variety of chronic inflammatory conditions, from autoimmune diseases to allograft rejection. [Copyright &y& Elsevier]

Short-time Proper Orthogonal Decomposition (POD) is proposed as an image-based technique to study the transient jet screech characteristics of moderately under-expanded supersonic jets emanating from a circular baseline and two bevelled nozzles. Time-resolved schlieren imaging of turbulent flow structures were performed with an ultrahigh-speed schlieren setup. Short-time POD was performed by systematically sampling image-series with a short time delay, performing PODs and applying spectral analyses on the first POD mode coefficients, and plotting the peak frequencies from the resulting PSDs into a peak frequency-occurrence count histogram. The results are in good agreement with the near-field noise spectra and wavelet transform analysis of the microphone measurements, which revealed intermittent jet screech occurrences at St=0.25 for both baseline and 30° bevelled jets, while none was detected for the 60° bevelled jet. In particular, the occurrence counts of the frequency bins is proposed as a suitable parameter to characterize the intermittent nature of jet screech, with the frequency bin revealing the jet screech frequency if present. The present study demonstrates the advantage of short-time POD analysis on time-resolved schlieren images over traditional image-based POD methods, which includes computational gains from parallelization, the ability to handle much larger datasets and revealing insights into a transient flow and noise phenomenon. [ABSTRACT FROM AUTHOR]

In this study, by phylogenetic analysis, we identified an epidemiological cluster involving eight individuals diagnosed with acute hepatitis B virus (HBV) infection related to unprotected sexual intercourse in a restricted area of central Italy (time period: 2011–2014). Notably, these patients (six of eight Italians) were infected by subgenotype F1b, which is not commonly found in western countries. Ultra-deep pyrosequencing confirmed a superimposable composition of HBV quasi-species in these patients. Despite the availability of effective vaccination, this study highlights the importance of not underestimating the risk of HBV infection, of continuing to set up surveillance programmes for HBV infection, and of investigating the pathogenetic potential of these atypical genotypes. [ABSTRACT FROM AUTHOR]