A new solution to the coupled problems of aero-propulsion system deceleration under supersonic state

Under supersonic state, the aero-propulsion system exhibits different coupled characters in deceleration from that in acceleration. However, the deceleration control has not been fully studied. In order to solve the coupled problems, an integrated component-level model including inlet and turbofan engine was established. Based on the integrated model, the particularity of inlet adjustment during deceleration was analyzed. And the analyzed results showed that the inlet regulation is not necessary to keep the inlet and engine working in well-matched at any time under supersonic state. Due to the coupled relationship between inlet and turbofan engine, a new optimal integrated control scheme is proposed in this paper. The inlet ramp angle is taken as an optimal control variable as the same as main fuel mass flow and nozzle throat area. The simulation results indicate that inlet ramp angle regulation showed a more effective control quality in the rapid drop of aero-propulsion–installed thrust. Furthermore, the deceleration could be completed in a shorter control time.

1307. The Mycoplasma Conundrum

Background Lockdown for Covid 19 between March 15 - 30, 2020 lead to sudden closures of schools, public gatherings, all but essential businesses, and stay-at-home orders. Between then and the end of April 2020, literally all enveloped respiratory viruses declined to virtually undetectable levels, suggesting a successful interruption of transmission. Weekly percentage positivity rates for M. pneumoniae and all other respiratory viruses from BioFire Syndromic Trends for weeks ending 3/7/2020- 4/24/2020. Weekly percentage positive rates are shown, with the Rhinovirus/Enterovirus rate divided by 3 and the M. pneumoniae rate multiplied by 10 to fit on the same scale. Methods We used the percentage positivity rates from BioFire Syndromic Trends and from GenMark Diagnostics to examine the post lockdown response of M. pneumoniae versus other respiratory viruses on the Respiratory Virus Panel (RP 2.0) Results As has been reported (Nawrocki J., et al, OFID 2021) and as shown in Figure 1, there was a rapid drop in the positivity rate for all enveloped respiratory viruses by 85.6% from an average rate of 2.014% positive for the week ending 3/14/20 to 0.29% for the week ending 4/18/20, while the positivity rate for M. pneumoniae actually increased by 44% from 0.536 % to 0.772%. The increase in M. pneumoniae positivity rate from its baseline of 0.51 ± 0.38 between 1/25/20 - 3/21/20 vs 0.71 ± 0.09 between 3/28/20 - 4/25/20 was significantly higher by t test, p=0.00574. Data from GenMark was available only monthly but also showed an upward rise from march to April, 2020. Conclusion It is well documented that M. pneumoniae is transmitted through respiratory mechanisms, yet lockdown measures sufficient to dramatically reduce ordinary respiratory virus transmission had no comparable effect on transmission of Mycoplasma pneumoniae. It is also well known that M. pneumoniae persists in the respiratory tract as long as months after an infection. Therefore, it is possible that this reservoir continued to be a source of transmission for M. pneumoniae, even though lockdown measures effectively interrupted the enveloped respiratory viruses. Disclosures Kenneth Rand, M.D., BioFire Diagnostics (Advisor or Review Panel member, Research Grant or Support)

Influence of a non-condensable gas on mixing of a melt with water in a stratified configuration

The influence of bubbles of hot non-condensable gas formed at the interface between the melt and water on the formation of a mixture of melt with water capable of producing steam explosions is considered. The dynamics of such a bubble in subcooled water is analyzed numerically in a one-dimensional spherically symmetric approximation. It is shown that with significant initial superheat of the bubble relative to the water, a rapid drop in pressure in the bubble occurs due to strong heat removal into the water. This leads to the collapse of the bubble and the appearance of an accompanying flow of water. The results obtained made it possible to approximately describe the stage of collapse of the bubble as the polytropic process and to determine its index. The axisymmetric problem of the impact of the water jet on the surface of a melt during collapse of a gas bubble near the interface between the melt and water is numerically investigated. In this case, the obtained polytropic process equation is used to determine the pressure in the bubble. It is found that the resulting impact on the melt is capable of knocking out melt droplets into the water to a height of several centimeters, which leads to the formation of a layer of water mixed with the melt droplets, which is capable of producing strong steam explosions.

Mass Spectrometry-Based Proteomics Reveal Alcohol Dehydrogenase 1B as a Blood Biomarker Candidate to Monitor Acetaminophen-Induced Liver Injury

Acute liver injury (ALI) is a severe disorder resulting from excessive hepatocyte cell death, and frequently caused by acetaminophen intoxication. Clinical management of ALI progression is hampered by the dearth of blood biomarkers available. In this study, a bioinformatics workflow was developed to screen omics databases and identify potential biomarkers for hepatocyte cell death. Then, discovery proteomics was harnessed to select from among these candidates those that were specifically detected in the blood of acetaminophen-induced ALI patients. Among these candidates, the isoenzyme alcohol dehydrogenase 1B (ADH1B) was massively leaked into the blood. To evaluate ADH1B, we developed a targeted proteomics assay and quantified ADH1B in serum samples collected at different times from 17 patients admitted for acetaminophen-induced ALI. Serum ADH1B concentrations increased markedly during the acute phase of the disease, and dropped to undetectable levels during recovery. In contrast to alanine aminotransferase activity, the rapid drop in circulating ADH1B concentrations was followed by an improvement in the international normalized ratio (INR) within 10–48 h, and was associated with favorable outcomes. In conclusion, the combination of omics data exploration and proteomics revealed ADH1B as a new blood biomarker candidate that could be useful for the monitoring of acetaminophen-induced ALI.

Trends in healthcare utilisation during COVID-19: a longitudinal study from the UK

ObjectiveThe first wave of the COVID-19 pandemic had a major impact on healthcare utilisation. The aim of this retrospective review was to quantify how utilisation of non-COVID care changed during this time so as to gain insight and inform planning of future services during potential second and subsequent waves.Methods and analysisA longitudinal design was used to analyse anonymous private UK health insurer datasets covering the period of January 2018 to August 2020. Taken as a measure of healthcare utilisation in the UK, incidence rates of claims broken down by service area and condition were calculated alongside overall monthly totals and costs. Pre-COVID-19 years were compared with the current year.ResultsHealthcare utilisation during the first wave of COVID-19 decreased by as much as 70% immediately after lockdown measures were implemented. After 2 months, the trend reversed and claims steadily began to increase, but did not reach rates seen from previous years by the end of August 2020. Assessment by service and diagnostic category showed that most areas, especially those highly reliant on in-person treatment, reflected the same pattern (ie, rapid drop followed by a steady recovery). The provision of mental health services differed from this observed trend, where utilisation increased by 20% during the first wave of COVID-19, in comparison to pre-COVID-19 years. The utilisation of maternity services and the treatment of existing cancers also stayed stable, or increased slightly, during this time.ConclusionsHealthcare utilisation in a UK-based privately insured population decreased dramatically during the first wave of the COVID-19 pandemic, being over 70% lower at its height. However, mental health services remained resilient during this time, possibly due to greater virtualisation of diagnostics and care.

An Enhanced Model For E-Service Quality of Mobile Banking

The increasing growth in mobile device users and the rapid drop in conventional and mobile data charges have given way for a provision of banking services and mobile banking to be precise. Banks are now extending their services from traditional means of banking to a self-service system. Recently, mobile banking has been growing exponentially, but there is still a lack of confidence by the users because of low e-service quality of mobile banking. Researchers have done many works on mobile banking but were focused more on adoption and user intentions which contributes to the marketing and promotion of mobile banking. Mobile banking has some specific characteristic which makes it different from other web-based e-services. So the previous studies lack specific in-depth mobile banking e-service quality, such as failure to define the e-service quality of mobile banking and identification of mobile banking dimensions. This study identified mobile banking's dimensions and attributes that received less attention and suggested an improved model for mobile banking's electronic service quality.

Velamentous cord insertion ruptured during labour leading to acute fetal blood loss

Umbilical cord rupture (UCR) in utero is a very rare and critical emergency that can cause fetal death within minutes. A 38-year-old nulliparous woman was admitted at 39 weeks in labour. Sudden watery vaginal discharge and bleeding with a rapid drop in the fetal heart rate to 60 beats/min necessitated an emergency caesarean section. A male infant weighing 2632 g was delivered 21 min after the onset of bradycardia; Apgar scores were 0 and 1 at 1 and 5 min, respectively. He was extremely pale; the umbilical arterial blood pH was 6.89 and haemoglobin was 9.0 g/dL. The umbilical cord had a velamentous insertion and was lacerated, with haemorrhage in the outer layer of an umbilical artery close to the placental end. The presentation was typical of UCR: vaginal bleeding following the rupture of membranes. Prompt diagnosis of UCR and termination of pregnancy are essential for fetal survival.

The Damage of Ocular Surface Due to Uncontrolled Intraocular Pressure in Neovascular Glaucoma

Neovascular Glaucoma (NVG) is a severe form of glaucoma characterized by neovascularization and the proliferation of fibrovascular tissue in the anterior chamber angle. Patients with NVG generally present with elevated intraocular pressure (IOP) and may experience severe pain. Ocular surface is affected by high IOP and can lead from moderated to marked conjunctival congestion that is frequently associated with edematous cornea. The aim of the study is to show how the high IOP can affect the ocular surface of the NVG patients and how we can treat and prevent the suffering. Materials and methods: We took in the study a number of 38 eyes from 35 patients with NVG in stage 3 with angle closure glaucoma, that presented high IOP and impaired ocular surface. Results and discussions: The ocular surface was damaged in patients that presented IOP between a minimum of 38 mmHg and maximum of 89 mmHg. The symptoms that patients presented were: conjunctival congestion in particular perikeratic, epithelial and stromal corneal edema, epithelial bubble, corneal ulcerations. Treatment followed rapid drop in IOP and the restoration and protection of ocular surface. The management of neovascular eye with high IOP was medical, laser and surgical. The restoration of ocular surface was made with lubricating hyperosmotic ophthalmic solutions, regenerative and protective agents. In all cases after the treatment was performed the ocular surface was restored. Conclusions: NVG is a very difficult pathology and is very hard to manage. The uncontrolled IOP in NVG patients affect the ocular surface and leads to complications. Long-term maintenance of normal intraocular pressure is important in NVG management but also in protecting the ocular surface.

Rid enhances the 6-hydroxypseudooxynicotine dehydrogenase reaction in nicotine degradation by Agrobacterium tumefaciens S33

Agrobacterium tumefaciens S33 degrades nicotine through a hybrid of the pyridine and pyrrolidine pathways. The oxidation of 6-hydroxypseudooxynicotine to 6-hydroxy-3-succinoyl-semialdehyde-pyridine by 6-hydroxypseudooxynicotine dehydrogenase (Pno) is an important step in the breakdown of the N-heterocycle in this pathway. Although Pno has been characterized, the reaction is not fully understood, i.e., it starts at a high speed, followed by a rapid drop in the reaction rate, leading to the formation of a very small amount of product. In this study, we speculated that an unstable imine intermediate is produced in the reaction, which may be toxic to the metabolism. We found that a Rid protein (designated as Rid-NC) encoded by a gene in the nicotine-degrading gene cluster enhanced the reaction. Rid is a widely distributed family of small proteins with various functions, and some subfamilies have deaminase activity to eliminate the toxicity of the reactive intermediate imine. Biochemical analyses showed that Rid-NC relieved the toxicity of the presumable imine intermediate produced in the Pno reaction, and that, in the presence of Rid-NC, Pno maintained a high activity and the amount of the reaction product was increase by at least 5-fold. Disruption of the rid-NC gene caused a slower growth of strain S33 on nicotine. The mechanism of Rid-NC-mediated detoxification of the imine intermediate was discussed. A phylogenetic analysis indicated that Rid-NC belongs to the rarely studied Rid6 subfamily. These results further our understanding of the biochemical mechanism of nicotine degradation and provide new insights into the function of the Rid6 subfamily proteins. IMPORTANCE Rid is a family of proteins that participate in metabolite-damage repair and is widely distributed in different organisms. In this study, we found that Rid-NC, which belongs to the Rid6 subfamily, promoted the 6-hydroxypseudooxynicotine dehydrogenase (Pno) reaction in the hybrid of the pyridine and pyrrolidine pathways for nicotine degradation by Agrobacterium tumefaciens S33. Rid-NC hydrolyzed the presumable reactive imine intermediate produced in the reaction to remove its toxicity on Pno. The finding furthers our understanding of the metabolic process of the toxic N-heterocyclic aromatic compounds in microorganisms. This study demonstrated that the Rid family of proteins also functions in the metabolism of N-heterocyclic aromatic alkaloids, in addition to the amino acid metabolism, and that Rid6-subfamily proteins also have deaminase activity, similar to RidA subfamily. The ability of reactive imines to damage a non-pyridoxal-5′-phosphate-dependent enzyme was reported. This study provides new insights into the function of the Rid family of proteins.

The effects of COVID-19 on Airbnb

COVID-19 pandemic starting at the end of 2019, hit hard tourism and hospitality industries throughout the world. As a part of the processes, the most popular P2P accommodation service, the Airbnb also faced a rapid drop in bookings. This study explores and compares the effects of the first wave of the pandemic on the Airbnb markets of 15 cities. The analysis is based on the data retrieved from Insideairbnb.com. Booking trends are compared between 2019 and 2020 and a day-to-day analysis of occupancy rates during the first months of 2020 is also performed. Special attention was paid to the effects of pandemic on different price categories of listings. The results show that the evolution of local pandemic situation had the most significant impact on bookings and occupancy rates in the investigated cities. The characteristics of local markets and the pandemic and economic situation of sending countries had also great influence on the bookings and cancellations. In addition, in some cases the cancellations did not affect the reservations made for the later periods, meaning that tourists hoped for a quick recovery. The effect on price categories was also different from one location to another. The study provides empirical insights to the effects of the disease on P2P accommodations. Furthermore, the future of short-term rentals is also discussed briefly.