Sports despite masks: no negative effects of FFP2 face masks on cardiopulmonary exercise capacity in children.

Face masks were recognized as one of the most effective ways to prevent the spread of the COVID-19 virus in adults. These benefits were extended to children and adolescents. However, the fear of negative consequences from wearing a face mask during physical exercise led to cancellations of physical education lessons. This further decreased the amount of physical activity available to children and adolescents during the pandemic. However, there is little published data on the potential adverse effects of wearing the most effective and partially mandatory FFP2/N95 face masks during PE or physical activity (PA) in this age. Even though the pandemic has been declared as passed by the WHO, the rise of a new pandemic and thus the use of face masks for limiting its spread is inevitable, so we need to be better prepared for alternative options to lockdown and limitation of PA in such a scenario. Twenty healthy children aged 8-10 years performed two identical cardiopulmonary exercise tests as an incremental step test on a treadmill within an interval of 2 weeks, one time without wearing a protective mask and one time wearing an FFP2 mask. The cardiopulmonary exercise parameter and especially the end-expiratory gas exchange for oxygen and carbon dioxide (petO2 and petCO2) were documented for each step, at rest and 1 min after reaching physical exhaustion. Twelve boys (mean age 8.5 ± 1.4 years) and 8 girls (mean age 8.8 ± 1.4 years) showed no adverse events until maximal exertion. The mean parameters measured at peak exercise did not differ significantly between both examinations (mean peak VO2 = 42.7 ± 9.5 vs 47.8 ± 12.9 ml/min/kg, p = 0.097, mean O2pulse 7.84 ± 1.9 ml/min vs. 6.89 ± 1.8, p = 0.064, mean VE/VCO2slope 33.4 ± 5.9 vs. 34.0 ± 5.3, p = 0.689). The only significant difference was the respiratory exchange rate (RER, 1.01 ± 0.08 vs 0.95 ± 0.08, p = 0.004). The measured respiratory gases (end-tidal O2 and CO2) decreased and respectively increased significantly in almost every step when wearing an FFP2 mask. However, these levels were well below hypercapnia and above hypoxia. CONCLUSION:  In this study, no significant differences in the cardiorespiratory function at peak exercise could be discerned when wearing an FFP2/N95 face mask. While the end-tidal values for CO2 increased significantly and the end-tidal values for O2 decreased significantly, these values did never reach levels of hypercapnia or hypoxia. Furthermore, the children terminated the exercise at a lower RER and heart rate (HR) suggesting a subconscious awareness of the higher strain. Since the detrimental effects of limiting sports during the pandemic are well documented, stopping PE lessons altogether because of the minor physiological effects of wearing these masks instead of simply stopping pushing children to perform at their best seems premature and should be reconsidered in the future. WHAT IS KNOWN: • Wearing a face mask has an influence on psychological, social, and physiological functions in adults. • Because of the observed effects of wearing face masks in adults, physical activity in children was limited during the pandemic. WHAT IS NEW: • Wearing an FFP2/N95 mask during physical activity did not lead to hypercapnia or hypoxia in children in this study. • Even though end-tidal CO2 values were significantly higher and end-tidal O2 values significantly lower when wearing an FFP2/N95 face mask, no pathological values were reached.

COPHYD (Corona Owed Physical Deficiency): The Impact of Lockdown on Cardiopulmonary Function in Paediatric Cardiology Patients.

INTRODUCTION: Due to the Corona-lockdowns the closure of sports facilities and schools has led to a decline in physical activity (PA) for months. PA is essential for maintaining cardiopulmonary function assessed by peak oxygen uptake. Since peak oxygen uptake represents the best predictor for mortality and morbidity in children with congenital heart disease the impact of lockdowns on this parameter is vital. METHODS: We evaluated retrospectively cardiopulmonary exercise data from our patient collective from before lockdown with twin-paired data from during lockdown. The twin-pairing was achieved by matching patients with similar heart disease, age, sex, and test method. Cardiopulmonary exercise testing was achieved on either the treadmill or the bicycle. RESULTS: We were able to twin-pair 90 cases (26 twins with heart disease and 19 healthy twins). There was a significant decrease of cardiopulmonary function (V̇O2peak: 35.7±9.8 vs.30.4±10.6) in the heart disease cohort along with a significant decrease in peak oxygen pulse (13.3±4.1 vs. 11.4±4.5), and peak minute ventilation (V ̇E: 83.05±29.08 vs.71,49±24.96). The healthy children improved over the timeframe, but this only reached significance for peak minute ventilation (81.72±25.79 vs.97.94±31.4). CONCLUSION: We observed a significant decline of peak oxygen uptake during lockdown in the group of congenital heart disease (CHD) patients. This involved a loss of cardiac function as well as pulmonary function. This could be explained by limited access to sports facilities and restriction of regular daily movement due to school closure and overprotection. Healthy children improved their pulmonary function. This might be an indication of an improvement of exercise during confinement.Aufgrund des Corona-Lockdowns hat die Schließung von Sportanlagen und Schulen über Monate zu einem Rückgang der körperlichen Aktivität geführt. Körperliche Aktivität ist für die Aufrechterhaltung der kardiopulmonalen Funktion, bewertet durch die maximale Sauerstoffaufnahme, unerlässlich. Da die maximale Sauerstoffaufnahme der beste Prädiktor für Mortalität und Morbidität bei Kindern mit angeborenen Herzerkrankungen ist, sind die Auswirkungen des Lockdowns auf diesen Parameter von entscheidender Bedeutung. Spiroergometriedaten unseres Patientenkollektivs aus der Zeit vor dem Lockdown wurde mit Daten von statistischen Zwillingen aus dem gleichen Kollektiv während des Lockdowns verglichen. Die Zwillingspaarung wurde erreicht, indem Patienten mit ähnlichen Herzerkrankungen, Alter, Geschlecht und Testmodalitäten verglichen wurden. Die Spiroergometrie wurde entweder auf dem Laufband oder auf dem Fahrrad durchgeführt. Insgesamt wurden 90 Datensätze verbunden (26 Zwillinge mit Herzkrankheit und 19 gesunde Zwillinge). In der Kohorte der Herzerkrankten konnte eine signifikante Verschlechterung der kardiopulmonalen Funktion (V̇O2peak: 35,7±9,8 vs. 30,4±10,6), des Spitzensauerstoffpulses (O2puls: 13,3±4,1 vs. 11,4±4,5) und der Spitzenminutenventilation (VE: 83,05 ± 29,08 vs. 71,49 ± 24,96) beobachtet werden. Die gesunden Kinder verbesserten sich im Laufe der Zeit, wobei der Anstieg nur bei der Spitzenminutenventilation (81,72±25,79 vs. 97,94 ± 31,4) signifikant war. in der Kohorte der Patienten mit angeborenen Herzerkrankungen (CHD) beobachteten wir einen deutlichen Rückgang der maximalen Sauerstoffaufnahme während des Lockdowns. Dies liegt begründet in einer Verschlechterung der Herz-, sowie der Lungenfunktion. Erklärung dafür könnte der begrenzte Zugang zu Sporteinrichtungen, sowie Einschränkungen der täglichen Bewegungsfreiheit durch Schulschließungen und Überbehütung sein. Gesunde Kinder konnten ihr Atemminutenvolumen während dem Lockdown steigern und zeigten einen Trend zu besserer Belastbarkeit. Dies könnte auf eine Zunahme der körperlichen Bewegung während des Lockdowns hindeuten.

THz-TDS Reflection Measurement of Coating Thicknesses at Non-Perpendicular Incidence: Experiment and Simulation.

Time-domain spectroscopy (TDS) in the terahertz (THz) frequency range is gaining in importance in nondestructive testing of dielectric materials. One application is the layer thickness measurement of a coating layer. To determine the thickness from the measurement data, the refractive index of the coating layer must be known in the surveyed frequency range. For perpendicular incidence of the radiation, methods exist to extract the refractive index from the measurement data themselves without prior knowledge. This paper extends these methods for non-perpendicular incidence, where the polarization of the radiation becomes important. Furthermore, modifications considering effects of surface roughness of the coating are introduced. The new methods are verified using measurement data of a sample of Inconel steel coated with yttria-stabilized zirconia (YSZ) and with COMSOL simulations of the measurement setup. To validate the thickness measurements, scanning electron microscopy (SEM) images of the layer structure are used. The results show good agreement with an average error of 1% for the simulation data and under 4% for the experimental data compared to reference measurements.

Brief report: Adult hippocampal precursor cells shorten S-phase and total cell cycle length during neuronal differentiation.

Cell cycle analyses of adult hippocampal neural stem and precursor cells in vivo are challenging, as there is no temporal or local discrimination of different precursor cell populations. All commonly used techniques to determine the cell cycle length of proliferating cells in the adult hippocampus do not allow discrimination between different cell types. Here, we introduce a novel procedure to precisely calculate cell cycle phase lengths of distinct precursor cell populations in vivo and thereby demonstrate a large heterogeneity of cell cycle kinetics within the pool of adult hippocampal precursor cells. Proliferating NeuroD1(+) cells exhibited a significantly faster S-phase progression (T(s) = 10.1 ± 0.6 hours) and shorter total cell cycle length (T(c) = 22.6 ± 0.1 hours) than NeuroD1(-) cells (T(s) = 13.5 ± 0.8 hours, T(c) = 27.0 ± 0.5 hours; p < .05). Dividing glial fibrillary acidic protein (GFAP(+)) cells also showed significantly shorter mean T(s) of 9.7 ± 0.6 hours and T(c) of 22.8 ± 0.5 hours compared to the rest of uncommitted NeuroD1(-) precursors (p < .01). Together, NeuroD1(+) neuronal progenitors and mitotic GFAP(+) radial glia-like cells divide significantly faster than amplifying neural progenitor cells by accelerating their S-phase. S-phase duration seems to determine cell cycle length in the adult hippocampus.

The absence of spatial echo suppression in the echolocating bats Megaderma lyra and Phyllostomus discolor.

Acoustic orientation most often takes place in echoic environments. The mammalian auditory system shows a variety of specializations to suppress misleading spatial information mediated by echoes. Psychophysically these specializations are summarized as the precedence effect. This study investigates how echolocating bats deal with multiple reflections of their sonar emissions from different spatial positions. In a two-alternative, forced choice paradigm, a study was made of the extent to which the echolocating bats Megaderma lyra and Phyllostomus discolor spontaneously suppress the spatial information of a second reflection of their sonar emission. The delay between the first and the second reflection ranged between 0 and 12.8 ms. In general, M. lyra (five individuals) and P. discolor (two individuals) did not suppress the spatial information of the second reflection of their sonar emission, whatever the delay. Only one M. lyra showed significant suppression for delays between 0.8 and 3.2 ms. However, this suppression could not be confirmed in an exact repetition of the experiment. The current data indicate that although bats may be able to suppress the spatial information of a second reflection, this is not their default mode of auditory processing. The reason for this exceptional absence of spatial echo suppression may lie in the shorter time constants of cochlear processing in the ultrasonic frequency range and the strong influence of cognitive components associated with the ;precedence effect'.