Fish Anchor Dived – Confirmation Through Field Tests in the Swan River

This paper reports the results from field tests on a 1/15th scale recently developed fish anchor. The tests were conducted at three locations in the Swan River, Perth. Two series of tests were performed from the Burswood and Maylands jetties with water depths between 1.1 and 1.9 m. The final series of tests were undertaken in deeper waters of 2.6 m from a barge. The riverbed at the Burswood Jetty and barge test location consisted of soft clay, and that at the Maylands Jetty comprised sandy silt. The tip embedment depths of the scaled fish anchor, with dry weight of 0.304 kN and impact velocity of 5.89∼9.55 m/s, in soft clay were 1.17∼2.40 times the anchor length. For similar impact velocities, the tip embedment depths in sandy silt were 30 ∼ 60% shallower than those in soft clay. By comparing the field test data in clay, the fish anchor achieved normalised embedment depths similar to those of the torpedo and OMNI-Max anchors under half or less impact velocity. Most importantly, the field tests confirmed the diving behaviour of the fish anchor under loading with mudline inclination of 20° and 25°, with the second peak dictated the capacity. The ultimate capacity was 5∼7 times the anchor submerged weight in water.

Changes in foot progression angle during gait reduce the knee adduction moment and do not increase hip moments in individuals with knee osteoarthritis

People with knee osteoarthritis who adopt a modified foot progression angle (FPA) during gait often benefit from a reduction in the knee adduction moment and knee pain. It is unknown, however, whether changes in the FPA increase hip moments, a surrogate measure of hip loading, which may increase the risk of hip pain or osteoarthritis. This study examined how altering the FPA affects hip moments. Individuals with knee osteoarthritis walked on an instrumented treadmill with their baseline gait, 10° toe-in gait, and 10° toe-out gait. A musculoskeletal modeling package was used to compute joint moments from the experimental data. Fifty participants were selected from a larger study who reduced their peak knee adduction moment with a modified FPA. In this group, participants reduced the first peak of the knee adduction moment by 7.6% with 10° toe-in gait and reduced the second peak by 11.0% with 10 ° toe-out gait. Modifying the FPA reduced the early-stance hip abduction moment, at the time of peak hip contact force, by 4.3% ± 1.3% for 10° toe-in gait (p=0.005) and by 4.6% ± 1.1% for 10° toe-out gait (p<0.001) without increasing the flexion and internal rotation moments (p>0.15). In summary, when adopting a FPA modification that reduced the knee adduction moment, participants did not increase surrogate measures of hip loading.

Vortex- and Wake-Induced Vibrations of a Circular Cylinder Placed in the Proximity of Two Fixed Cylinders

Purpose This study aims to understand the vibratory response of a circular cylinder placed in proximity to other fixed bodies. Methods A circular cylinder model was placed in a circulating water channel and was supported elastically to vibrate in the water. Another two circular cylinders were fixed upstream of the vibrating cylinder. The temporal displacement variations of the vibrating cylinder were measured and processed by a frequency analysis. Results When the inline spacings were small, two amplitude peaks appeared in the reduced velocity range 3.0–13.0. When the inline spacings were large, the amplitude response showed a single peak. Conclusion For small inline spacings, the first peak was attributed to high-amplitude vibrations forced by Karman vortex streets shed from the upstream cylinders. The second peak arose from interactions of the wakes of the upstream cylinder with the vibrating cylinder. When the inline spacing increased, the vortex-induced vibrations resembled those of an isolated cylinder.

Sympathetic Response to Postural Perturbation in Stance

The purpose of the present study was to elucidate whether the sympathetic response to perturbation in stance represents multiple mental responses, whether perturbation-induced fear of fall is one of the mental responses, and whether the sympathetic response is task specific. While healthy humans maintained stance, the support surface of the feet translated in the forward or backward direction. The phasic electrodermal response (EDR), representing the sympathetic response, appeared 1–1.5 s after the support surface translation. Mostly, perturbation-induced EDRs comprised one peak, but some EDRs were comprised of two peaks. The onset latency of the two-peak EDR was much shorter than that of the one-peak EDR. The second peak latency of the two-peak EDR was similar to the peak latency of the one-peak EDR, indicating that the first peak of the two-peak EDR was an additional component preceding the one-peak EDR. This finding supports a view that perturbation-induced EDR in stance sometimes represents multiple mental responses. The amplitude of the EDR had a positive and significant correlation with fear, indicating that perturbation-induced EDR in stance partially represents perturbation-induced fear of fall. The EDR amplitude was dependent on the translation amplitude and direction, indicating that perturbation-induced EDR in stance is a task specific response. The EDR appeared earlier when the participants prepared to answer a question or when the perturbation was self-triggered, indicating that adding cognitive load induces earlier perturbation-induced mental responses.

446 Relationship between out of hospital cardiac arrest and COVID-19 pandemic: impact on outcome

Aims During 2020, Italy was hit by the pandemic of the ‘Coronavirus disease 2019’ (COVID-19) with an incidence/100 000 citizens characterized by two peaks. An increase in out-of-hospital cardiac arrest (OHCA) mortality during the first pandemic peak has already been described, but there are few data on the whole year. The goal of our study is to evaluate the impact of the pandemic on post-OHCA mortality. Methods We considered patients with OHCA in Varese territory from January to December 2020 with medical aetiology according with Utstein 2014 classification. The primary endpoint of the study was the assessment of acute post-arrest mortality and which parameters influence this outcome. In particular, both the role of pandemic peaks (‘first peak’ from 11 March 2020 to 23rd May 2020 and ‘second peak’ from 7 October 2020 to 31 December 2020) and the average rescue times, i.e.: (i) interval between OHCA and call for first aid (delay in activation of assistance); (ii) the interval between the call and the arrival of the rescue vehicles (delay in the arrival of the first aid) and finally; (iii) the time between the arrival of the rescue vehicles and the end of Cardiopulmonary Resuscitation (CPR), interrupted due to death or Recovery of Spontaneous Circulation (ROSC). Finally, we performed a multivariate analysis to assess which of the variables considered had the greatest impact on the outcome. Results We analysed 708 patients (mean age 76 + 14.09 years; 40% women). Overall mortality was 89%. During the peaks there was an increase in mortality compared to the pre-pandemic period (first peak 96% vs. 83%, OR 4.49; second peak 92% vs. 83%, OR 2.45) (Figure 1). The time between the collapse and the call for help was significantly higher during the first pandemic peak compared to the second peak and the pre-pandemic period (P = 0.003); the time between the call and the arrival on the patient was significantly longer during both pandemic peaks than in the previous period (P = 0.002) and there was no significant difference in CPR duration time between the periods analysed. In a multivariate model, the only time associated with an increase in mortality is the period between the call for help and the arrival on the patient, regardless of the COVID-19 pandemic. Conclusions During the COVID-19 pandemic there has been an increase in mortality of patients with OHCA. Among the variables considered, the increase in mortality is mainly associated with the delay in the arrival of emergency vehicles on site. This delay, although decreasing, was also maintained during the second peak of the pandemic.

Detection and abundance of SARS-CoV-2 in wastewater in Liechtenstein, and the estimation of prevalence and impact of the B.1.1.7 variant

The new coronavirus 2 (SARS-CoV-2) is known to be also shed through feces, which makes wastewater-based surveillance possible, independent of symptomatic cases and unbiased by any testing strategies and frequencies. We investigated the entire population of the Principality of Liechtenstein with samples from the wastewater treatment plant Bendern (serving all 39,000 inhabitants). Twenty-four-hour composite samples were taken once or twice a week during a period of 6 months from September 2020 to March 2021. Viral RNA was concentrated using the PEG centrifugation method followed by reverse transcription quantitative PCR. The aim of this research was to assess the suitability of COVID-19 fragments to relate the viral wastewater signal to the incidences and assess the impact of the emerging B.1.1.7. variant. The viral load in the wastewater peaked at almost 9 × 108 viral fragments per person equivalent (PE) and day on October 25, and showed a second peak on December 22 reaching a viral load of approximately 2 × 108 PE−1d−1. Individual testing showed a lag of 4 days and a distinct underestimation of cases at the first peak when testing frequency was low. The wastewater signal showed an immediate response on the implementation of non-pharmaceutical interventions. The new virus variant B.1.1.7. was first detected in wastewater on December 23, while it was first observed with individual testing not before January 13, 2021. Further, our data indicate that the emergence of new virus variant may change the wastewater signal, probably due to different shedding patterns, which should be considered in future models.

Priming with Retinoic Acid, an Active Metabolite of Vitamin A, Increases Vitamin A Uptake in the Small Intestine of Neonatal Rats

Given that combined vitamin A (VA) and retinoic acid (RA) supplementation stimulated the intestinal uptake of plasma retinyl esters in neonatal rats, we administrated an RA dose as a pretreatment before VA supplementation to investigate the distinct effect of RA on intestinal VA kinetics. On postnatal days (P) 2 and 3, half of the pups received an oral dose of RA (RA group), while the remaining received canola oil as the control (CN). On P4, after receiving an oral dose of 3H-labeled VA, pups were euthanized at selected times (n = 4–6/treatment/time) and intestine was collected. In both CN and RA groups, intestinal VA mass increased dramatically after VA supplementation; however, RA-pretreated pups had relatively higher VA levels from 10 h and accumulated 30% more VA over the 30-h study. Labeled VA rapidly peaked in the intestine of CN pups and then declined from 13 h, while a continuous increase was observed in the RA group, with a second peak at 10 h and nearly twice the accumulation of 3H-labeled VA compared to CN. Our findings indicate that RA pretreatment may stimulate the influx of supplemental VA into the intestine, and the increased VA accumulation suggests a potential VA storage capacity in neonatal intestine.

On the molecular mechanism of excitation–transcription coupling in skeletal muscle

An important question in neuromuscular biology is how skeletal muscle cells decipher the stimulation pattern coming from motoneurons to define their phenotype-activating transcriptional changes in a process named excitation–transcription coupling. We have shown in adult muscle fibers that 20 Hz electrical stimulation (ES) activates a signaling cascade that starts with Cav1.1 activation, ATP release trough pannexin-1 channel, activation of purinergic receptors, and IP3-dependent Ca2+ signals inducing transcriptional changes related to muscle plasticity from fast to slow phenotype. Extracellular addition of 30 µM ATP mimics transcriptional changes induced by ES at 20 Hz. ATP release occurs in two peaks, the first around 15 s after ES and a second around 300 s after ES. In the present work, we used apyrase to hydrolyze ATP 60 s after ES, maintaining the first peak and eliminating the second peak. In this condition, transcriptional changes were abolished, indicating that the second peak is the one crucial to activate transcription. Additionally, we observed a small depolarization of fibers after ES. The addition of 30 to 100 µM external ATP also induced depolarization of muscle fibers. This depolarization was unable to activate contraction but was able to induce transcriptional changes induced by 20 Hz ES. These changes were completely inhibited by the IP3R blocker xestospongin B, suggesting that IP3-dependent events are triggered at these membrane depolarization values. Moreover, transcriptional changes induced by addition of 30 µM extracellular ATP was blocked by incubation of fibers with 25 µM Nifedipine. These results suggest that the second ATP peak observed after 20 Hz ES is responsible for transcriptional activation by inducing small depolarizations of fiber membranes that are also sensed by Cav1.1. Finally, we show evidence that downstream of purinergic receptors, PKC is activated, likely causing phosphorylation of ClC-1 chloride channels, possibly responsible for depolarization after 20 Hz.

Spacecraft launch and re-entry: Effects of simulated +Gx acceleration on cardiorespiratory parameters

Introduction: In the spaceflight, during launch and re-entry, the crew is exposed to acceleration ranging from +4Gx to +8Gx in nominal conditions. This study was conducted to assess the changes in cardiorespiratory parameters, namely, heart rate (HR), electrocardiogram (ECG), respiratory rate (RR), and SpO2 on exposure to simulated +Gx acceleration. Material and Methods: Fifteen randomly selected healthy male volunteers participated in the study. They were exposed to a simulated acceleration profile consisting of two peaks in the high-performance human centrifuge; first peak of +4Gx for 30 s and second peak of+8Gx for 30 s. The cardiorespiratory parameters were monitored and recorded during the acceleration exposure. The data were compiled and analyzed using one-way repeated measures ANOVA. Results: Significant increase in HR was observed on exposure to +4Gx (110.4 ± 16.7 bpm; P < 0.001) in comparison to the baseline value (80.5 ± 7.5 bpm). However, the changes in the HR at +8Gx were not significant in comparison to baseline as well as +4Gx values. On the other hand, RR indicated a significant increase on exposure to +8Gx (25.2 ± 5.8 breaths/min) in comparison to the baseline (15.1 ± 1.6 breaths/min; P = 0.001) and +4Gx (19.0 ± 6.1 breaths/min; P = 0.009) values. SpO2 showed a significant reduction at +8Gx (94.2 ± 3.8%) in comparison to baseline (98.9 ± 0.3%; P = 0.004) and +4Gx (96.9 ± 1.5%; P = 0.003). ECG did not show any evidence of arrhythmia during the exposure to +Gx acceleration. Conclusion: The insignificant changes in the HR at peak of +8Gx indicate less pronounced effects on the smaller hydrostatic gradient in +Gx acceleration unlike +Gz acceleration. However, the findings of the study point towards a significant increase in respiratory rate and reduction in SpO2 at +8Gx.