[Seisunix] Modeling Covid-19 with Seismic Unix

Juan Lorenzo Diaz Naveas juan.diaz at pucv.cl
Mon Apr 6 00:36:16 CEST 2020


Dear John,

Useful contribution to the understanding of the epidemiology of this
disease.

I hope that all Seismic Unix family is safe and healthy

Juan




El dom., 5 abr. 2020 a las 14:53, Francisco Neto (<fasn.ufpa at gmail.com>)
escribió:

> Good to know John
>
> Very intersting
>
> Thanks
>
> Em dom, 5 de abr de 2020 3:39 PM, John Stockwell <john.19071969 at gmail.com>
> escreveu:
>
>>
>> I send my good wishes to all of you and I hope that you, your families,
>> and your friends are faring well in this difficult time.
>>
>> For those who are interested in modeling populations, such as the current
>> epidemic, there is a logistic equation solver called
>> “verhulst” in the SU package which you may find of interest.
>>
>> For example for Covid-19 cases in the US, taking 22 January as day 0 of
>> cases in the US and 29 February as day 0 for deaths. Respective
>> stepmax= values of 72 for cases and 34 for deaths are both 3 April
>>
>>
>> verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=x > calculated_cases.bin
>>
>> verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=x > calculated_deaths.bin
>>
>> xgraph < calculated_cases.bin n=72 nplot=1 d1=1 &
>>
>> xgraph < calculated_deaths.bin n=34 nplot=1 d1=1 &
>>
>> The growth rate a1 values are determined empirically from publicly
>> available data, in this case from the CDC and from the Worldometer site.
>> You will have to make your own estimate of a1 for the data that you are
>> modeling.
>>
>> Another parameter that is harder to get is an estimate of the carrying
>> capacity of the system a2. Here I am assuming a maximum of 1 million cases
>> in the US and 100 thousand deaths.
>>
>> The number of new cases or deaths per day is measured by the derivative
>> of the solutions to the verhulst equation
>>
>> verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=y > delta_cases.bin
>>
>> verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=y > delta_deaths.bin
>>
>> xgraph < delta_cases.bin n=72 nplot=1 d1=1 &
>>
>> xgraph < delta_deaths.bin n=34 nplot=1 d1=1 &
>>
>> The peak in the change of the population per day occurs when the
>> population reaches the exactly half of the carrying capacity of the system.
>> Thus, raising the carrying capacity will increase the height of the peak
>> and move it out later in time.
>>
>> Take care, everyone and stay safe.
>>
>> -John
>>
>> John Stockwell
>> Visit: https://wiki.Seismic-Unix.org
>> The new home of Seismic Un*x
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