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The validity of the Oberbeck–Boussinesq (OB) approximation in Rayleigh–Bénard (RB) convection is studied using the Gray & Giorgini (Intl J. Heat Mass Transfer, vol. 19, 1976, pp. 545–551) criterion that requires that the residuals, i.e. the terms that distinguish the full governing equations from their OB approximations, are kept below a certain small threshold 
$\hat {\sigma }$. This gives constraints on the temperature and pressure variations of the fluid properties (density, absolute viscosity, specific heat at constant pressure 
$c_p$, thermal expansion coefficient and thermal conductivity) and on the magnitudes of the pressure work and viscous dissipation terms in the heat equation, which all can be formulated as bounds regarding the maximum temperature difference in the system, 
$\varDelta$, and the container height, 
$L$. Thus for any given fluid and 
$\hat {\sigma }$, one can calculate the OB-validity region (in terms of 
$\varDelta$ and 
$L$) and also the maximum achievable Rayleigh number 
${{Ra}}_{max,\hat {\sigma }}$, and we did so for fluids water, air, helium and pressurized SF
$_6$ at room temperature, and cryogenic helium, for 
$\hat {\sigma }=5\,\%$, 
$10\,\%$ and 
$20\,\%$. For the most popular fluids in high-
${{Ra}}$ RB measurements, which are cryogenic helium and pressurized SF
$_6$, we have identified the most critical residual, which is associated with the temperature dependence of 
$c_p$. Our direct numerical simulations (DNS) showed, however, that even when the values of 
$c_p$ can differ almost twice within the convection cell, this feature alone cannot explain a sudden and strong enhancement in the heat transport in the system, compared with its OB analogue.
Every year in the month of September, National Suicide Prevention Week is celebrated. The goal of suicide prevention week is to inform the public about suicide prevention, primarily the warning signs of suicide. However, the impact of this month on the general population is unknown. The Google trends show how frequent web searches have been performed for a particular search-term, which provide an approximation of the people’s interest.
To evaluate public interest in suicide prevention by analyzing the google trends of “Suicide Prevention” search-term.
We estimated the interest in such topics by running the google trends data of the last decade by using the filter [Search Term:“Suicide Prevention”, Locations: “United States” and Time Ranges “ 2010 to 2020”].
During this specific interval, people have searched “Suicide Prevention” most frequently during the month of September (month of National Suicide Prevention week). Conversely, in the other months, interest in “suicide prevention” fluctuated between little to none. The only other time people have shown interest in Suicide prevention, other than the month of September, was with suicide news in the media, such as the death of a celebrity by suicide, or suicide-related TV shows. [Figure]
Although it is not definitive, it gives some idea that National Suicide Prevention week has a considerable impact on population interest. Since we did not observe sufficient public interest in other months, there should be frequent and systematic efforts to spread suicide prevention awareness among the general population.
