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BackgroundHypergravity environment is a kind of extreme environment that human beings will inevitably encounter when they realize space navigation. When the body is affected by a hypergravity load, the instantaneous changes in fluid distribution cause abnormalities in the physiological functions of the heart and blood vessels. Whether to adapt to these extreme conditions is an important link for humans to break through the Earth’s exploration of space.MethodThis study adopts the experimental method of simulating hypergravity, using amphibian frog larvae as the research object, to observe the structural changes of the unique single ventricle of amphibian frog larvae after being subjected to hypergravity load. Combining digital simulation technology, this study explores the possible impact of hypergravity load on ventricular function. The experiment selected frog larvae (Larvae, commonly known as tadpoles) and subjected them to a continuous load of 10 minutes under a rotating supergravity state of +3Gz for 3wks. The hypergravity load experiment ends when the larvae develop into young frogs (Metamorphs). After the specimen is subjected to histochemical fixation treatment, it is then embedded, sliced, stained, and subjected to computer-assisted microscopy to obtain heart slice images. With the help of computer-assisted image analysis, the length, axis, and ratio of the ventricles are calculated, and the morphological changes of the ventricles are analyzed.ResultsResearch shows that the impact of hypergravity fields on the heart is multifaceted. Due to prolonged and intermittent hypergravity load stimulation, the swimming mode of juvenile frogs has changed from a normal symmetrical swing of the tail to a dominant swimming mode on one side. The vestibular nucleus discharge record shows that after hypergravity load, the activity of vestibular nucleus discharge in juvenile frogs is lower than that in the control group, indicating that simulated hypergravity load has an effective stimulating effect on the development of amphibian frogs from larvae to juveniles. Hypergravity also causes the heart to shift to the right within the chest cavity, resulting in elongated ventricles with an imbalance in the ratio between the longitudinal and transverse axes, indicating a possible decrease in filling capacity.ConclusionThe experimental results of this study suggest that the hypergravity loading environment during space navigation can affect ventricular structure, and changes in this structure can reduce cardiac ejection function. Starting from the conclusion that prolonged intermittent hypergravity loads can affect heart development, it is necessary to consider how to develop protective equipment to alleviate the thoracic space bearing hypergravity loads, reduce cardiac anatomical displacement and ventricular structural imbalance, and ensure that the body maintains normal cardiac blood supply function in the airspace environment. This is a topic that needs further exploration in the future.

As the ravages caused by COVID-19 pandemic are becoming inevitable with every moment, monitoring and understanding of transmission and fatality rate has become even more paramount for containing its spread. The key purpose of this analysis is to report the real-time effective reproduction rate ($R_t$ ) and case fatality rates (CFR) of COVID-19 in South Asia region. Data for this study are extracted from JHU CSSE COVID-19 Data source up to July 31, 2020. $R_t$ is estimated using exponential growth and time-dependent methods. R0 package in R-language is employed to estimate $R_t$ by fitting the existing epidemic curve. Case fatality rate is estimated by using Naive and Kaplan-Meier methods. Owing to exponential increase in cases of COVID-19, the pandemic will ensue in India, Maldives and in Nepal as $R_t$ was estimated greater than 1 for these countries. Although case fatality rates are found lesser as compared to other highly affected regions in the world, strict monitoring of deaths for better health facilities and care of patients is emphasized. More regional level cooperation and efforts are the need of time to minimize the detrimental effects of the virus.