Escher's Room

Marrink, Siewert-Jan and Herman J. C. Berendsen. "Simulation of Water Transport through a Lipid Membrane." The Journal of Physical Chemistry 98, no. 15 (1994): 4155--4168. Marrink and Berendsen describe the headgroups of DPPC as "dipolar" (p. 4161).  Phosphatidylcholine contains both a negatively charged phosphate and a positively charged choline, hence the descriptor.  Another name would be zwitterion, wherein a molecule contains both a positively charged and negatively charged group but whose net charge is neutral. Because of the polar nature of the the DPPC headgroup, they observed a "very diffuse interface between the dipolar headgroups and water" (p. 4161).

 "An investor could lose the full principal value of his/her investment within a single day if the index loses more than 33% in one day." ... Largest daily percentage losses in the S&P 500 Index since 1957 [1]  1. 1987-10-19   -20.47%  2. 1929-10-28   -12.34%  3. 2020-03-16   -11.98%  4. 1929-10-29   -10.16%  5. 1929-11-06   - 9.92%  6. 2020-03-12   - 9.51%  7. 1937-10-18   - 9.27%  8. 2008-10-15   - 9.04%  9. 2008-12-01   - 8.93% 10. 1933-07-20   - 8.88% A 33% loss in one day has not occurred since 1957.  I suppose it's unlikely to occur, but there's always a chance.  Even the worst market shock due to the recent pandemic was -12%.  What would cause a 33% loss? This is called tail risk, right? [1] "List of largest daily changes in the S&P 500 Index." Wikipedia. Last edited on 2 July 2022 11:11 CDT. https://en....