Satellite Constellation Pattern Optimization for Complex Regional Coverage

The use of regional coverage satellite constellations is on the rise, urging the need for an optimal constellation design method for complex regional coverage. Traditional constellations are often designed for continuous global coverage, and the few existing regional constellation design methods lead to suboptimal solutions for periodically time-varying or spatially-varying regional coverage requirements. This paper introduces a new general approach to design an optimal constellation pattern that satisfies such complex regional coverage requirements. To this end, the circular convolution nature of the repeating ground track orbit and common ground track constellation is formalized. This formulation enables a scalable constellation pattern analysis for multiple target areas and with multiple sub-constellations. The formalized circular convolution relationship is first used to derive a baseline constellation pattern design method with the conventional assumption of symmetry. Next, a novel method based on binary integer linear programming is developed, which aims to optimally design a constellation pattern with the minimum number of satellites. This binary integer linear programming method is shown to achieve optimal constellation patterns for general problem settings that the baseline method cannot achieve. Five illustrative examples are analyzed to demonstrate the value of the proposed new approach.Comment: 47 pages, 23 figures, Journal of Spacecraft and Rockets (Published

A fatal case of COVID-19 pneumonia due to possible pulmonary thrombosis

The relationship between the severity of COVID-19, hyperinflammation, and intravascular oagulopathy is of critical importance. We report on a case of severe COVID-19 pneumonia treated with favipiravir during the earliest phase of the pandemic. The present case showed improvement in SARS-CoV-2 viral load and the presence of SARS-CoV-2 IgG with decreased radiological evidence of pulmonary infiltration. Moreover, the levels of serum IL-6 and TNF-α did not increase markedly. However, the hypoxia failed to recover, leading to the patient’s death due to possible pulmonary thrombosis, because D-dimer was markedly elevated, and an electrocardiogram showed typical changes. At present, the fact that some COVID-19 patients with mild to moderate symptoms suddenly die at home has become a major issue in Japan. These findings suggest that additional treatment with anti-coagulants should be considered in some COVID-19 patients at risk of ypercoagulation to prevent sudden death from pulmonary thrombosis

The development of an affinity evaluation and prediction system by using protein–protein docking simulations and parameter tuning

Koki Tsukamoto1, Tatsuya Yoshikawa1,2, Kiyonobu Yokota1, Yuichiro Hourai1, Kazuhiko Fukui11Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST), Koto-ku, Tokyo, Japan; 2Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Toyonaka, Osaka, JapanAbstract: A system was developed to evaluate and predict the interaction between protein pairs by using the widely used shape complementarity search method as the algorithm for docking simulations between the proteins. We used this system, which we call the affinity evaluation and prediction (AEP) system, to evaluate the interaction between 20 protein pairs. The system first executes a “round robin” shape complementarity search of the target protein group, and evaluates the interaction between the complex structures obtained by the search. These complex structures are selected by using a statistical procedure that we developed called ‘grouping’. At a prevalence of 5.0%, our AEP system predicted protein–protein interactions with a 50.0% recall, 55.6% precision, 95.5% accuracy, and an F-measure of 0.526. By optimizing the grouping process, our AEP system successfully predicted 10 protein pairs (among 20 pairs) that were biologically relevant combinations. Our ultimate goal is to construct an affinity database that will provide cell biologists and drug designers with crucial information obtained using our AEP system.Keywords: protein–protein interaction, affinity analysis, protein–protein docking, FFT, massive parallel computin