Spatio-temporal propagation of COVID-19 pandemics

The new coronavirus known as COVID-19 is spread world-wide since December 2019. Without any vaccination or medicine, the means of controlling it are limited to quarantine and social distancing. Here we study the spatio-temporal propagation of the first wave of the COVID-19 virus in China and compare it to other global locations. We provide a comprehensive picture of the spatial propagation from Hubei to other provinces in China in terms of distance, population size, and human mobility and their scaling relations. Since strict quarantine has been usually applied between cities, more insight about the temporal evolution of the disease can be obtained by analyzing the epidemic within cities, especially the time evolution of the infection, death, and recovery rates which affected by policies. We study and compare the infection rate in different cities in China and provinces in Italy and find that the disease spread is characterized by a two-stages process. At early times, at order of few days, the infection rate is close to a constant probably due to the lack of means to detect infected individuals before infection symptoms are observed. Then at later times it decays approximately exponentially due to quarantines. The time evolution of the death and recovery rates also distinguish between these two stages and reflect the health system situation which could be overloaded.

Different emotion faces stimulation in patients with major depressive disorder by Event-related Potential N170 / 中国神经精神疾病杂志

Objective To investigate effects of three kinds of neutral,happy,sad emotional faces stimulus on sustained attention task using N170 in depression patients to analysis the correlation of depression in patients with depression,anxiety severity and the amplitude and latency of N170.Methods Twenty-eight patients with depression aged from 22 to 69 years (case group),and 31 healthy controls (control group) aged from 20 to 61 years were recruited for the study.Subjects were asked to perform tasks in the selection of attention following randomly presented three kinds of happy,neutral and sad emotional faces stimuli.Brain auditory evoked potential including N170 amplitude and latency were recorded during the tasks.HAMD and HAMA were used to assess the severity of depression and anxiety.Results There was significant difference between case group and control group in N170 latency by three kinds of happy,neutral and sad emotional faces stimulation in the local skull (T5,T6,O1,O2) (P＜0.05).But the difference was not significant in N170 amplitude (P＞0.05).The total score of HAMD in case group had a positive correlation with N170 amplitude by neutral facial emotion stimulation in part of T5 (r=0.443,P=0.018).Conclusion There is significant change in the initial cognitive processing of different emotional faces in the patients with depression.And the severity of depression is related to the N170 amplitude induced by the neutral emotional faces stimulation in some parts of brain.