LES of non-Newtonian physiological blood flow in a model of arterial stenosis

Large Eddy Simulation (LES) is performed to study the physiological pulsatile transition-to-turbulent non-Newtonian blood flow through a 3D model of arterial stenosis by using five different blood viscosity models: (i) Power-law, (ii) Carreau, (iii) Quemada, (iv) Cross and (v) modified-Casson. The computational domain has been chosen is a simple channel with a biological type stenosis formed eccentrically on the top wall. The physiological pulsation is generated at the inlet of the model using the first four harmonic series of the physiological pressure pulse (Loudon and Tordesillas [1]). The effects of the various viscosity models are investigated in terms of the global maximum shear rate, post-stenotic re-circulation zone, mean shear stress, mean pressure, and turbulent kinetic energy. We find that the non-Newtonian viscosity models enlarge the length of the post-stenotic re-circulation region by moving the reattachment point of the shear layer separating from the upper wall further downstream. But the turbulent kinetic energy at the immediate post-lip of the stenosis drops due to the effects of the non-Newtonian viscosity. The importance of using LES in modelling the non-Newtonian physiological pulsatile blood flow is also assessed for the different viscosity models in terms of the results of the dynamic subgrid-scale (SGS) stress Smagorinsky model constant, C<sub>s</sub>, and the corresponding SGS normalised viscosity

The Strategies of the Spanish cotton textile companies before the Civil War: the road to longevity

This study, based on family business theories, offers an innovative vision of the Spanish cotton industry. It proves that Spanish cotton companies, just like their European counterparts, implemented a strategy that was consistent with their nature as family businesses and went beyond the economic-institutional frames within which they developed. The article identifies this strategy as `conservative, because its main objectives were longevity and family control and because it was based on a high percentage of own resources, low levels of indebtedness and organic growth, thus sacrificing profitability for the sake of security.Universidad Pablo de OlavidePostprin

Foreign divestment and international rationalisation in the motor industry The sale of Chrysler (UK) to Peugot

SIGLEAvailable from British Library Lending Division - LD:9116.77(86) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The role of wetland coverage within the near-stream zone in predicting of seasonal stream export chemistry from forested headwater catchments

Stream chemistry is often used to infer catchment-scale biogeochemical processes. However, biogeochemical cycling in the near-stream zone or hydrologically connected areas may exert a stronger influence on stream chemistry compared with cycling processes occurring in more distal parts of the catchment, particularly in dry seasons and in dry years. In this study, we tested the hypotheses that near-stream wetland proportion is a better predictor of seasonal (winter, spring, summer, and fall) stream chemistry compared with whole-catchment averages and that these relationships are stronger in dryer periods with lower hydrologic connectivity. We evaluated relationships between catchment wetland proportion and 16-year average seasonal flow-weighted concentrations of both biogeochemically active nutrients, dissolved organic carbon (DOC), nitrate (NO 3 -N), total phosphorus (TP), as well as weathering products, calcium (Ca), magnesium (Mg), at ten headwater (<200 ha) forested catchments in south-central Ontario, Canada. Wetland proportion across the entire catchment was the best predictor of DOC and TP in all seasons and years, whereas predictions of NO 3 -N concentrations improved when only the proportion of wetland within the near-stream zone was considered. This was particularly the case during dry years and dry seasons such as summer. In contrast, Ca and Mg showed no relationship with catchment wetland proportion at any scale or in any season. In forested headwater catchments, variable hydro

Preclinical and clinical studies of photobiomodulation therapy for macular oedema

Published: 14 July 2020AIMS/HYPOTHESIS:Diabetic macular oedema (DME) is the leading cause of visual impairment in people with diabetes. Intravitreal injections of vascular endothelial growth factor inhibitors or corticosteroids prevent loss of vision by reducing DME, but the injections must be given frequently and usually for years. Here we report laboratory and clinical studies on the safety and efficacy of 670 nm photobiomodulation (PBM) for treatment of centre-involving DME. METHODS:The therapeutic effect of PBM delivered via a light-emitting diode (LED) device was tested in transgenic mice in which induced Müller cell disruption led to photoreceptor degeneration and retinal vascular leakage. We also developed a purpose-built 670 nm retinal laser for PBM to treat DME in humans. The effect of laser-delivered PBM on improving mitochondrial function and protecting against oxidative stress was studied in cultured rat Müller cells and its safety was studied in pigmented and non-pigmented rat eyes. We then used the retinal laser to perform PBM in an open-label, dose-escalation Phase IIa clinical trial involving 21 patients with centre-involving DME. Patients received 12 sessions of PBM over 5 weeks for 90 s per treatment at a setting of 25, 100 or 200 mW/cm2 for the three sequential cohorts of 6-8 patients each. Patients were recruited from the Sydney Eye Hospital, over the age of 18 and had centre-involving DME with central macular thickness (CMT) of >300 μm with visual acuity of 75-35 Log minimum angle of resolution (logMAR) letters (Snellen visual acuity equivalent of 20/30-20/200). The objective of this trial was to assess the safety and efficacy of laser-delivered PBM at 2 and 6 months. The primary efficacy outcome was change in CMT at 2 and 6 months. RESULTS:LED-delivered PBM enhanced photoreceptor mitochondrial membrane potential, protected Müller cells and photoreceptors from damage and reduced retinal vascular leakage resulting from induced Müller cell disruption in transgenic mice. PBM delivered via the retinal laser enhanced mitochondrial function and protected against oxidative stress in cultured Müller cells. Laser-delivered PBM did not damage the retina in pigmented rat eyes at 100 mW/cm2. The completed clinical trial found a significant reduction in CMT at 2 months by 59 ± 46 μm (p = 0.03 at 200 mW/cm2) and significant reduction at all three settings at 6 months (25 mW/cm2: 53 ± 24 μm, p = 0.04; 100 mW/cm2: 129 ± 51 μm, p < 0.01; 200 mW/cm2: 114 ± 60 μm, p < 0.01). Laser-delivered PBM was well tolerated in humans at settings up to 200 mW/cm2 with no significant side effects. CONCLUSIONS/INTERPRETATION:PBM results in anatomical improvement of DME over 6 months and may represent a safe and non-invasive treatment. Further testing is warranted in randomised clinical trials. TRIAL REGISTRATION:ClinicalTrials.gov NCT02181400 Graphical abstract.Weiyong Shen, Kelvin Yi Chong Teo, John P. M. Wood, Anagha Vaze ... Glyn Chidlow ... Robert Casson ... et al