Background There is no evidence supporting that temperature changes COVID-19 transmission. Methods We collected the cumulative number of confirmed cases of all cities and regions affected by COVID-19 in the world from January 20 to February 4, 2020, and calculated the daily means of the average, minimum and maximum temperatures in January. Then, restricted cubic spline function and generalized linear mixture model were used to analyze the relationships. Results There were in total 24,232 confirmed cases in China and 26 overseas countries. In total, 16,480 cases (68.01%) were from Hubei Province. The lgN rose as the average temperature went up to a peak of 8.72℃ and then slowly declined. The apexes of the minimum temperature and the maximum temperature were 6.70℃ and 12.42℃ respectively. The curves shared similar shapes. Under the circumstance of lower temperature, every 1℃ increase in average, minimum and maximum temperatures led to an increase of the cumulative number of cases by 0.83, 0.82 and 0.83 respectively. In the single-factor model of the higher-temperature group, every 1℃ increase in the minimum temperature led to a decrease of the cumulative number of cases by 0.86. Conclusion The study found that, to certain extent, temperature could significant change COVID-19 transmission, and there might be a best temperature for the viral transmission, which may partly explain why it first broke out in Wuhan. It is suggested that countries and regions with a lower temperature in the world adopt the strictest control measures to prevent future reversal.

No abstract

Local densities of fundamental physical quantities, including stress and heat flux fields, are formulated for atomistic systems involving three-body forces. The obtained formulas are calculable within an atomistic simulation, in consistent with the conservation equations of thermodynamics of continuum, and can be applied to systems with general two- and three-body interaction forces. It is hoped that this work may correct some misuse of inappropriate formulas of stress and heat flux in the literature, may clarify the definition of site energy of many-body potentials, and may serve as an analytical link between an atomistic model and a continuum theory. Physical meanings of the obtained formulas, their relation with virial theorem and heat theorem, and the applicability are discussed.

No abstract

No abstract

2016-11-02T18:49:00

No abstract

In this paper we present a new formalism that analytically links atomic variables to continuously distributed local properties and that leads to a concurrent two-level representation of balance laws for atomistic systems with general lattice structure. The new component of this formulation is an explicit decomposition of associated fluxes in multiatomic lattices into components representing the distortions of lattice cells and the rearrangement of atoms within the lattice cells. New formulation of balance laws is obtained in a form that is suitable for a direct atomistic analysis at fine scale to a continuum analysis in coarse scales. The results of this work will provide a new continuum field representation of classical N-body dynamics that can fully reproduce phonon dispersion relations of multiatomic crystalline materials and will enable coupled atomistic and continuum simulations within a single theoretical framework.