A Kinetic Energy Preserving DG Scheme Based on Gauss–Legendre Points

In the context of numerical methods for conservation laws, not only the preservation of the primary conserved quantities can be of interest, but also the balance of secondary ones such kinetic energy in case of the Euler equations of gas dynamics. In this work, we construct a kinetic energy preserving discontinuous Galerkin method on Gauss–Legendre nodes based on the framework of summation-by-parts operators. For a Gauss–Legendre point distribution, boundary terms require special attention. In fact, stability problems will be demonstrated for a combination of skew-symmetric and boundary terms that disagrees with exclusively interior nodal sets. We will theoretically investigate the required form of the corresponding boundary correction terms in the skew-symmetric formulation leading to a conservative and consistent scheme. In numerical experiments, we study the order of convergence for smooth solutions, the kinetic energy balance and the behaviour of different variants of the scheme applied to an acoustic pressure wave and a viscous shock tube. Using Gauss–Legendre nodes results in a more accurate approximation in our numerical experiments for viscous compressible flow. Moreover, for two-dimensional decaying homogeneous turbulence, kinetic energy preservation yields a better representation of the energy spectrum.     

Efficient disease detection in gastrointestinal videos – global features versus neural networks

Multimedia Tools and Applications - Analysis of medical videos from the human gastrointestinal (GI) tract for detection and localization of abnormalities like lesions and diseases requires both...     

Preparation of (PbxBa1-x)TiO3 thin films by MOCVD using an aerosol-assisted liquid delivery system

Abstract

Thin films of PbTiO₃, BaTiO₃ and (Pb_xBa_1-x)TiO₃ (PBT) have been prepared by metal-organic chemical vapor deposition using a horizontal reactor with an aerosol-assisted liquid delivery system. Structural and electrical properties have been investigated as a function of the lead content x. First results on PBT thin films grown on platinized silicon substrates show, for x < 0.8, an increasing tetragonal distortion of the lattice cell (c/a >1), and accompanying ferroelectric behavior which is similar to the bulk material. For smaller lead content (x < 0.8) no ferroelectric behavior is established and a small tetragonal distortion of opposite type (c/a <1) is observed. This distortion is attributed to a thermally induced tensile film stress and may be responsible for the suppression of the ferroelectric phase transition.     

Zirconia Transport by Liquid Convection during Oxidation of Zirconium Diboride–Silicon Carbide

During high-temperature oxidation of ZrB₂–SiC composites, a multi-layer oxide scale forms with a silica-rich borosilicate liquid as the surface oxide layer. Here, a recently proposed novel mechanism for the high-temperature oxidation of ZrB₂–SiC composites is further investigated and verified. This mechanism involves the formation of convection cells in the oxide surface layer during high-temperature oxidation of the composite. The formation of zirconia deposits found in the center of the convection cells is proposed here to be the consequence of liquid transport. The nature and deposition mechanism of the zirconia is reported in detail, using calculated phase equilibrium diagrams and microstructure observations of a ZrB₂-15 vol% SiC composite tested at 1550° and 1700°C in ambient air for various times. The calculated phase equilibrium diagrams for the binary ZrO₂–B₂O₃ system as well as the ternary B₂O₃–SiO₂–ZrO₂ system at 1500°C are reported here to interpret these results.     

Rapid Oxidation Characterization of Ultra-High Temperature Ceramics

Here, a novel method for testing ultra-high-temperature ceramics (UHTC) at a high temperature, rapidly, at a low cost is introduced. A self-supported, self-heated ribbon specimen is used with a table-top apparatus to achieve the necessary high temperatures. This method enables a large temperature–time–composition parameter space to be covered by rapidly producing a large set of postoxidation samples for analysis. The complex oxide scale known to form during oxidation of UHTC materials is shown to be easily reproduced using this method. A ZrB₂–SiC (15 vol%) UHTC material was tested at 1700° C for 15 min. The oxide scale consists of a thin outermost silica (SiO₂) layer and a zirconia (ZrO₂) columnar layer with small amounts of SiO₂ embedded between the ZrO₂ columns. A region of SiC-depleted zone was observed between the unreacted core and the ZrO₂ layer. The measured thickness of the oxide scale was 102 μm and ∼120 μm for the SiC-depleted zone.     

Growth strategies in creative industries

In recent years there has been increased emphasis, in both academic and political arenas, on the economic importance of the creative industries (CIs). As a result, policymakers are increasingly looking to the CIs as a source of potential growth. The literature on CIs suggests that these industries are predominantly content based rather than market based, with artistic priorities taking precedence over business concerns. This research examines growth strategies in the CIs using qualitative and quantitative methods. An in‐depth case study of 23 firms in CIs suggests that these firms tend to view growth as a secondary goal compared to the goal of creative output. The case study further yields the proposition that firms in the CIs can benefit from adopting what we refer to as an accordion growth strategy, in which firms grow and shrink to accommodate artistic content as well as in response to external forces. Statistical analysis of survey data confirms that firms in the CIs are less likely to have ambitions to grow and more likely to adopt an accordion growth strategy than firms in technology industries. These findings suggest that the policy emphasis on growth in the CIs might be misguided and should allow for alternating periods of growth and shrinkage.     

Mulch N recycling in green manure leys under Scandinavian conditions

Nitrogen (N) recycling to the regrowth of mulched red clover (Trifolium pratense L.) and mulched mixed red clover/perennial ryegrass (Lolium perenne L.) leys was determined in field experiments during three consecutive years using ¹⁵N-labelled shoot material. Nitrogen recycling was greater in the pure clover stands than in the mixed stands in the beginning of the growing season, but increased successively in the mixed stands so that it was similar (14–15.5%) in both stands at the end of the season. This recycling of N from the mulch led to increased biomass accumulation but did not alter stand composition in the mixed stands. Mulch-derived N was incorporated into the soil organic N in both pure clover and mixed stands which thus contributed to building up soil fertility. An approximately similar proportion of N remained unaccounted for in mulched pure clover and mixed stand leys and presumably represented gaseous losses. To exploit the benefits of green manure leys in the humid temperate zone while minimising the negative environmental impact, these should be harvested rather than mulched.     

Differential,Stage Dependent Detection of Peptidylarginine Deiminases and Protein Deimination in Lewy Body Diseases—Findings from a Pilot Study

Over 10 million people worldwide live with Parkinson’s disease (PD) and 4% of affected people are diagnosed before the age of 50. Research on early PD-related pathways is therefore of considerable importance. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that, through post-translational deimination of arginine to citrulline, contribute to changes in protein function, including in pathological processes. Recent studies have highlighted roles for PADs in a range of neurological disorders including PD, but overall, investigations on PADs in Lewy body disease (LBD), including PD, are still scarce. Hence, the current pilot study aimed at performing an immunohistochemistry screen of post-mortem human brain sections from Braak stages 4-6 from PD patients, as well as patients with incidental LBD (ILBD). We assessed differences in PAD isozyme detection (assessing all five PADs), in total protein deimination/citrullination and histone H3 deimination—which is an indicator of epigenetic changes and extracellular trap formation (ETosis), which can elicit immune responses and has involvement in pathogenic conditions. The findings of our pilot study indicate that PADs and deimination are increased in cingulate cortex and hippocampus, particularly in earlier stages of the disease. PAD2 and PAD3 were the most strongly upregulated PAD isozymes, with some elevation also observed for PAD1, while PAD4 and PAD6 increase was less marked in PD brains. Total protein deimination and histone H3 deimination were furthermore increased in PD brains, with a considerable increase at earlier Braak stages, compared with controls. Our findings point to a significant contribution of PADs, which may further aid early disease biomarker discovery, in PD and other LBDs.