Discontinuity in equilibrium wave–current ripple size and shape caused by a winnowing threshold in cohesive sand–clay beds

Sediments composed of mixed cohesive clay and non-cohesive sand are widespread in a range of aquatic environments. The dynamics of ripples in mixed sand–clay substrates have been studied under pure current and pure wave conditions. However, the effect of cohesive clay on ripple development under combined currents and waves has not been examined, even though combined flows are common in estuaries, particularly during storms. Based on a series of large flume experiments on ripple development under combined flows, we identified a robust inverse relationship between initial bed clay content, C0, and ripple growth rate. The experimental results also revealed two distinct types of equilibrium combined-flow ripples on mixed sand–clay beds: (a) large asymmetrical ripples with dimensions and plan geometries comparable to clean-sand counterparts for C0 ≤ 10.6%; and (b) small, flat ripples for C0 > 11%. The increase in bed cohesion contributed to this discontinuity, expressed most clearly in a sharp reduction in equilibrium ripple height, and thus a significant reduction in bed roughness, which implies that the performance of existing ripple predictors can be improved by the incorporation of this physical cohesive effect. These improvements are particularly important for sediment transport and morphodynamic models in muddy estuarine environments. For C0 ≤ 10.6%, strong clay winnowing efficiency under combined flows resulted in the formation of equilibrium clean-sand ripples and clay loss at depths far below the ripple base. In natural environments, this ‘deep cleaning’ of bed clay may cause a concurrent sudden release of a large amount of pollutants during storms, and lead to a sudden reduction in post-storm resistance to erosion of mixed sand–clay substrates.

Relationships between Workload, Heart Rate Variability, and Performance in a Recreational Endurance Runner

Background: The association between heart rate variability (HRV), training load (TL), and performance is poorly understood. Methods: A middle-aged recreational female runner was monitored during a competitive 20-wk macrocycle divided into first (M1) and second mesocycle (M2) in which best performances over 10 km and 21 km were recorded. Volume (km), session rating of perceived exertion (sRPE), TL, and monotony (mean TL/SD TL) were the workload parameters recorded. The root mean square of the successive differences in R-R intervals (RMSSD), its coefficient of variation (RMSSDcv), and the RMSSD:RR ratio were the HRV parameters monitored. Results: During M2, RMSSD (p = 0.006) and RMSSD:RR (p = 0.002) were significantly increased, while RR was significantly reduced (p = 0.017). Significant correlations were identified between monotony and volume (r = 0.552; p = 0.012), RR (r = 0.447; p = 0.048), and RMSSD:RR (r = −0.458; p = 0.042). A sudden reduction in RMSSD (from 40.31 to 24.34 ms) was observed the day before the first symptoms of an influenza. Conclusions: The current results confirm the practicality of concurrent HRV and sRPE monitoring in recreational runners, with the RMSSD:RR ratio indicative of specific adaptations. Excessive training volume may be associated to both elevated monotony and reduced RMSSD:RR. Identification of mesocycle patterns is recommended for better individualization of the periodization used.

Suspension syndrome

Suspension syndrome is a potentially fatal event of unknown incidence that can be caused by motionless hanging in the rope during rope-secured activities. During prolonged hanging, generalized hypoperfusion with reduced cerebral blood flow and consecutive loss of consciousness occurs. Two mechanisms are discussed as the cause leading to loss of consciousness: venous pooling in the legs and a sudden reduction of heart rate and blood pressure, similar to a neurocardiogenic syncope. The most important preventive measure is the activation of the muscle pump during hanging. In principle, the treatment follows standard <C>ABCDE care. The patient should be rescued from the hanging position as fast as possible and airway obstruction caused by hyperflexion of the head during unconscious hanging has to be reversed. There is an increased risk of hyperkalemia. Therefore, ECG monitoring should be established as soon as possible to recognize cardiac arrhythmias. Pulmonary embolism should be considered as a potentially reversible cause of cardiac arrest. Hypothermia prophylaxis and treatment have high priority. For suspension longer than two hours, a medical treatment facility able to provide continuous renal replacement therapy should be chosen. There is no evidence that laying a patient flat immediately after rescue is harmful. Key Words: Neurocardiac Syncope, Venous Pooling, Rescue Death, Generalized Hypoperfusion, Standard <C>ABCDE Care

Potential Effects of the COVID-19 Pandemic through Changes in Outbound Tourism on Water Demand: The Case of Liège (Belgium)

The COVID-19 pandemic has led to many countries closing their borders, and numerous people spending their holidays at home instead of traveling abroad. This sudden reduction in travel activities, and other ‘new normals’, might have influenced people’s water usage. Hence, using Liège as a case study, this study aims to address the potential effect of outbound tourism on water consumption and how the current situation might affect the total water demand. Statistical models were developed and validated using the total daily volume of 23 municipalities in the Liège conurbation, the monthly total number of outbound trips, and other meteorological data. Results suggest significantly lower water demand in the months with high numbers of outbound travel activities. Though the projected risk of increased water needs due to fewer people traveling is moderate, the threat becomes much higher during long periods of dry and hot weather.

P1362Diagnostic accuracy of R-wave detection by insertable cardiac monitors

OnBehalf 1.Department of Cardiology, Ghent University Hospital, Ghent, Belgium Introduction Insertable cardiac monitors (ICM) allow automatic arrhythmia detection but the diagnostic performance can be hampered by poor R-wave sensing leading to false positive recordings. Purpose This study assesses the prevalence and predictors of R-wave under- and oversensing among different ICM types. Methods Patients implanted with an ICM at the University Hospital of Ghent between January 2017 and August 2018 were included. All ICM tracings recorded at ICM interrogation or transmitted by remote monitoring were reviewed for inadequate R-wave sensing leading to false arrhythmia alerts. Inadequate R wave sensing was defined as undersensing due to sudden reduction in R wave amplitude or oversensing due to the occurrence of artefacts. Patient and implant characteristics were retrieved from the medical record and implant reports. Results The study screened 135 patients (age 59 ± 19 years, 44% female) implanted with different ICM types: Reveal XT and LINQ n = 92 (68%), Confirm and Confirm Rx n = 35 (26%), BioMonitor n = 8 (6%). ICM analysis was conducted in 112 patients (83%). Overall, false arrhythmia alerts due to inadequate R wave sensing occurred in 22 (20%) of the patients. Among these 22 patients, false diagnosis of bradycardia or pauses were documented in 64%, false high ventricular rates in 14% and false atrial fibrillation alerts in 22% of the patients. Of interest, in an additional 7 (6%) patients significant changes in R wave sensing occurred, although not causing false arrhythmic alerts. Occurrence of R-wave changes occurred in 19% of Reveal, 17% of Confirm and 50% of BioMonitor ICMs (p = not significant). Occurrence of R-wave changes among the different types of ICMs were not related to age, sex, BMI, time of the day, heart frequency or implant R-wave sensing. Conclusion Poor R wave sensing, leading to false arrhythmia detection, occurred in a significant number of ICM, and seems to occur independent of ICM type, patient or implant characteristics. Abstract Figure.

ANALYSIS OF LIQUID MEDIATED CONTACT OF GLASS COLLOIDAL PARTICLE WITH POLYSTYRENE COATED SURFACE

Spin coating has been widely used for obtaining uniform thin polymeric coating over glass surfaces. Previous studies have shown that the thin-coated film can deform and bulge out upon immersion in liquid. Such deformations can affect various properties of the films. In this study, we have analyzed the interaction of glass colloidal particle and the polystyrene (PS) spin-coated surface immersed in deionized (DI) water. It was found that the glass colloidal particle interacts with the surface in dissimilar way at various locations on the surface. A sudden reduction in the forces was also observed at different locations on the same surface. The separation distances at which the sudden change in the force occurred was closer to the height of the spherical domains. Therefore, the change could be attributed to the presence of blisters on the surface formed due to permeation of water into the thin film-substrate interface.

FE Analysis of Curved Castellated Girder for Variable Thermal Condition

Castellated girders having straight or curved profile are extensively used in structural application due to its aesthetics, versatility, economy and ease of use. The present paper is focused on Finite Element Analysis of curved castellated steel beam. The prime objective is to study the impact of opening and rise on behaviour of these curved steel beams. A parametric study has been conducted on arched castellated girder for various ratio of depth to opening for variable degree of curvature proportional to the span of the girder. The main focus of study in this paper is the temperature variation that exists between building interior and external environment. The FEA study reveals from the results that mid span deflection of beam increases with increase in size of opening. It is also observed that there is a sudden reduction of stresses when the span to rise ratio is reduced from 7 to 6.

Flight test of fault-tolerant flight control system using simple adaptive control with PID controller

Purpose This paper aims to demonstrate the effectiveness of a fault-tolerant flight control method by using simple adaptive control (SAC) with PID controller. Design/methodology/approach Numerical simulations and flight tests are executed for pitch angle and roll angle control of research aircraft MuPAL-α under the following fault cases: sudden reduction in aileron effectiveness, sudden reduction in elevator effectiveness and loss of longitudinal static stability. Findings The simulations and flight tests reveal the effectiveness of the proposed SAC with PID controller as a fault-tolerant flight controller. Practical implications This research includes implications for the development of vehicles’ robustness. Originality/value This study proposes novel SAC-based flight controller and actually demonstrates the effectiveness by flight test.