Mask wearing in pre-symptomatic patients prevents SARS-CoV-2 transmission: An epidemiological analysis.

OBJECTIVES: Pandemic COVID-19 has become a seriously public health priority worldwide. Comprehensive strategies including travel restrictions and mask-wearing have been implemented to mitigate the virus circulation. However, detail information on community transmission is unavailable yet. METHODS: From January 23 to March 1, 2020, 127 patients (median age: 46 years; range: 11-80) with 71 male and 56 female, were confirmed to be infected with the SARS-CoV-2 in Taizhou, Zhejiang, China. Epidemiological trajectory and clinical features of these COVID-19 cases were retrospectively retrieved from electronic medical records and valid individual questionnaire. RESULTS: The disease onset was between January 9 to February 14, 2020. Among them, 64 patients are local residents, and 63 patients were back home from Wuhan from January 10 to 24, 2020 before travel restriction. 197 local residents had definite close-contact with 41 pre-symptomatic patients back from Wuhan. 123 and 74 of them contact with mask-wearing or with no mask-wearing pre-symptomatic patients back from Wuhan, respectively. Data showed that incidence of COVID-19 was significantly higher for local residents close-contact with no mask-wearing Wuhan returned pre-symptomatic patients (19.0% vs. 8.1%, p < 0.001). Among 57 close-contact individuals, 21 sequential local COVID-19 patients originated from a pre-symptomatic Wuhan returned couple, indicated dense gathering in congested spaces is a high risk for SARS-CoV-2 transmission. CONCLUSIONS: Our findings provided valuable details of pre-symptomatic patient mask-wearing and restriction of mass gathering in congested spaces particularly, are important interventions to mitigate the SARS-CoV-2 transmission.

Necessary and sufficient conditions for the stability of a sleeping top described by three forms of dynamic equations.

Necessary and sufficient conditions for the stability of a sleeping top described by dynamic equations of six state variables, Euler equations, and Poisson equations, by a two-degree-of-freedom system, Krylov equations, and by a one-degree-of-freedom system, nutation angle equation, is obtained by the Lyapunov direct method, Ge-Liu second instability theorem, an instability theorem, and a Ge-Yao-Chen partial region stability theorem without using the first approximation theory altogether.

Synchronization of chaotic systems with uncertain chaotic parameters by linear coupling and pragmatical adaptive tracking.

We study the synchronization of general chaotic systems which satisfy the Lipschitz condition only, with uncertain chaotic parameters by linear coupling and pragmatical adaptive tracking. The uncertain parameters of a system vary with time due to aging, environment, and disturbances. A sufficient condition is given for the asymptotical stability of common zero solution of error dynamics and parameter update dynamics by the Ge-Yu-Chen pragmatical asymptotical stability theorem based on equal probability assumption. Numerical results are studied for a Lorenz system and a quantum cellular neural network oscillator to show the effectiveness of the proposed synchronization strategy.

Novel Fuzzy Modeling and Synchronization of Chaotic Systems With Multinonlinear Terms by Advanced Ge-Li Fuzzy Model.

Ge and Li proposed an alternative strategy to model and synchronize two totally different nonlinear systems in the end of 2011, which provided a new version for fuzzy modeling and has been applied to several fields to simplify their modeling works and solve the mismatch problems [1]-[17]. However, the proposed model limits the number of nonlinear terms in each equation so that this model could not be used in all kinds of nonlinear dynamic systems. As a result, in this paper, a more efficient and comprehensive advanced-Ge-Li fuzzy model is given to further release the limitation and improve the effectiveness of the original one. The novel fuzzy model can be applied to all kinds of complex nonlinear systems--this is the universal strategy and only m x 2 fuzzy rules as well as two linear subsystems are needed to simulate nonlinear behaviors (m is the number of states in a nonlinear dynamic system), whatever the nonlinear terms are copious or complicated. Further, the fuzzy synchronization of two nonlinear dynamic systems with totally distinct structures can be achieved via only two sets of control gains designed through the novel fuzzy model as well as its corresponding fuzzy synchronization scheme. Two complicated dynamic systems are designed to be the illustrations, Mathieu-Van der pol system with uncertainties and Quantum-cellular neural networks nano system with uncertainties, to show the effectiveness and feasibility of the novel fuzzy model.

Anti-control of chaos of single time-scale brushless DC motor.

Anti-control of chaos of single time-scale brushless DC motors is studied in this paper. In order to analyse a variety of periodic and chaotic phenomena, we employ several numerical techniques such as phase portraits, bifurcation diagrams and Lyapunov exponents. Anti-control of chaos can be achieved by adding an external constant term or an external periodic term.

[Investigation of single nucleotide polymorphisms in the promoter region of mannan-binding lectin gene in Bais, Uars and Lahus ethnics from China].

AIM: To investigate the single nucleotide polymorphisms(SNP) in the promoter region of mannan-binding lectin (MBL) gene in Bais, Uars and Lahus ethnics. METHODS: 71, 73 and 94 blood samples were obtained from Bais, Uars and Lahus subjects, respectively from Yunnan province. Genomic DNA was isolated from leucocytes. Polymorphism alleles -550(G/C, named H/L alleles), -220(G/C, X/Y alleles) and +4(C/T, P/Q alleles) in the promoter region of MBL gene were detected by sequence-specific primer-PCR and molecular beacon real-time PCR, and the frequencies of haplotypes and genotypes were analyzed. RESULTS: The frequencies of genotypes in Bais, Uars and Lahus ethnics were as follows: LYP/LYP 4(5.6%), 4(5.5%)and 2(2.1%); HYP/LYQ 6(8.5%), 11(15.1%) and 12(12.8%); LYP/LYQ 21(29.6%), 14(19.2%) and 51(54.3%); LXP/LXP 1(1.4%), 2(2.7%)and 0,LYQ/LYQ 10(14.1%); 14(19.2%), 7(7.4%), LXP/LYQ 10(14.1%), 13(17.8%) and 15(16.0%); HYP/LYP 4(5.6%), 3(4.1%) and 4(4.3%); HYP/LXP 3(4.2%), 1(1.4%) and 0; HYP/HYP 12(16.9%), 11(15.1%) and 3(3.2%). CONCLUSION: The distribution of alleles L/H is statistically different among Uars, Bais and Larhus(P<0.01), while X/Y and P/Q are not statistically significant(P>0.05). All studied haplotypes and genotypes are statistically different among the 3 ethnics(P<0.01). Genotypes LYP/LYQ and LXP/LYQ are common in all the 3 ethnics.