@Szabolcs V 12.1 just crashed again. This time I wrote down what happened. I quit local kernel from menu, followed by Trying to evaluate an open notebook. And FE hangs, had to terminate Mathematica.
something very strange happened now. I never seen it before. V 12.1. I made some changes to a notebook A. Saved the notebook each time after each change. And run things OK so I can see my changes took effect. Next FE hanged so had to restart Mathematica. Now I see ALL my changes I made in the same notebook are lost. How could this be possible? Since I was saving the notebook each time. Doesn't mathematica save the notebook to disk when one does save?
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2763473 March 30, 2020 Possible Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in a Public Bath Center in Huai’an, Jiangsu Province, China
This is concerning. "The bath center for men was approximately 300 m^2, with temperatures from 25 to 41 °C and humidity of approximately 60%." We might not see the pandemic slowing down during summer..
@Silvia I would have guessed that it's not so much the temperature, but the UV radiation of the sun that makes it harder for viruses during the summer. Additionally, more people are outside and not in confined spaces.
All these things do not apply for a bath (if it's the kind of bath I imagine).
@halirutan Good point on UV radiation! I also saw people talking about treatment under the sun during the 1918 flu and it worked better. I don't really know the lifestyle in EU or US, but in Singapore, because the weather is warm all the year, people are actually most of the time staying under the roof with A/C. There are confined sidewalks among mega malls and office buildings.
Now an on-topic question. Is this a bug or I did it wrong?
The two results are inconsistent for region of k < 0.
Easy-to-copy code: Integrate[Piecewise[{{1, x < k}}, 0], {x, y} \[Element] Disk[{0, 0}, 1], Assumptions -> -1 < k < 1]
