Search

This paper discusses the modeling activity of the NATO-STO Research Task Group AVT-349. The aim of this group is to improve the understanding and modeling of boundary layers in the complex flow around water vehicles. As such, the focus is on incompressible, high-Reynolds-number flows that can be subject to non-equilibrium conditions such as strong pressure gradients, three-dimensionality, and surface roughness and heterogeneity. The Task Group has identified a reduced number of simpler problems in which the above conditions can be studied separately and in controlled environments. These include two-dimensional rough-wall boundary layers under both zero and non-zero pressure gradients, two-dimensional smooth-wall boundary layers subject to pressure gradients, and boundary layers around smooth bodies of revolution and three-dimensional obstacles. An experimental and computational data set is being assembled for further analysis and insight into the flow mechanisms involved, as well as the shortcomings of state-of-the-art models. This paper gives an outlook of the modeling effort within the Task Group, as well its different objectives. These include predicting the effect of roughness in equilibrium conditions; assessing the applicability and/or extension of equilibrium models and predictions to non-equilibrium conditions, in particular when outer-layer similarity is lost; the development of near-wall models based on a reduced-order resolvent framework; and the use of machine-aided methods in closure models.

Aim: Recent evidence suggests that arterial hypertension could be alternatively explained as a physiological adaptation response to water shortage, termed aestivation, which relies on complex multi-organ metabolic adjustments to prevent dehydration. Here, we tested the hypothesis that chronic water loss across diseased skin leads to similar adaptive water conservation responses as observed in experimental renal failure or high salt diet. Methods: We studied mice with keratinocyte-specific overexpression of IL-17A which develop severe psoriasis-like skin disease. We measured transepidermal water loss and solute and water excretion in the urine. We quantified glomerular filtration rate (GFR) by intravital microscopy, and energy and nitrogen pathways by metabolomics. We measured skin blood flow and transepidermal water loss (TEWL) in conjunction with renal resistive indices and arterial blood pressure. Results: Psoriatic animals lost large amounts of water across their defective cutaneous epithelial barrier. Metabolic adaptive water conservation included mobilization of nitrogen and energy from muscle to increase organic osmolyte production, solute-driven maximal anti-diuresis at normal GFR, increased metanephrine and angiotensin 2 levels, and cutaneous vasoconstriction to limit TEWL. Heat exposure led to cutaneous vasodilation and blood pressure normalization without parallel changes in renal resistive index, albeit at the expense of further increased TEWL. Conclusion: Severe cutaneous water loss predisposes psoriatic mice to lethal dehydration. In response to this dehydration stress, the mice activate aestivation-like water conservation motifs to maintain their body hydration status. The circulatory water conservation response explains their arterial hypertension. The nitrogen-dependency of the metabolic water conservation response explains their catabolic muscle wasting. © 2021 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.

Magnetic Particle Imaging (MPI) ist ein neues Bildgebungsverfahren. Mit ihr kann die Verteilung magnetischer Nanopartikel im Organismus mit hoher Sensitivität quantitativ und ortsaufgelöst nachgewiesen werden. Das MPI-Verfahren zeichnet sich zudem durch eine sehr hohe zeitliche Auflösung[zum vollständigen Text gelangen Sie über die oben angegebene URL], 87. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie