Dylan K Wainwright et al. indicated high-performance Tuna platform for designing autonomous underwater vehicles [1]. Although their research will be useful, they should focus on the role of fins. Vadim Pavlov, et al. described hydraulic control of tuna fins [2]. During the late 18th century, wing designs were based on anatomical studies on dolphins, trout and tuna by the “father of aerodynamics”, Sir George Cayley [3,4]. Fish that are adapted for fast swimming, like tuna, are generally fusiform in shape and this is considered an efficient, hydrodynamic shape [5,6]. The hydraulic-fin-manufacture utilized multiple small fins instead of large hydraulic fins through the experiment for adopting better boat stabilizers [7]. By using two, four or six smaller active fins grouped together, the more small fins system produces better results without causing drag and slowing boats [7]. Tuna has such efficient hydrodynamic multiple small fins including 1st dorsal fin, 2nd dorsal fin, finlets, caudal fin, pelvic fin, pectoral fin, and anal fin. Every tuna fin may have the special role for better performance in stabilization of any vehicles.References:1. Dylan K Wainwright and George V Lauder 2020 Bioinspir. Biomim.15 0350072. Vadim Pavlov, et al., Hydraulic control of tuna fins: A role for the lymphatic system in vertebrate locomotion, Science, 21 Jul 2017, Vol.357, Issue 6348, pp.310-3143. Bio-mimetic Drag Reduction – Part 2: Aero- and Hydrodynamics, March 31, 2012http://aerospaceengineeringblog.com/bio-mimetic-drag-reduction-2/4. https://en.wikipedia.org/wiki/George_Cayley5. Eric Pickhartz, The ‘Tuna Robot’ is the Navy’s Newest Underwater Drone, July 4, 2014http://www.wideopenspaces.com/tuna-robot-navys-newest-underwater-drone/6. Kirk Janowiak, Are fish aerodynamic?, Jan 12, 2015https://www.quora.com/Are-fish-aerodynamic7. High-Performance Active Fin Stabilizers Improve Boat Speed and Performance, Feb 21, 2017http://www.gyrogalestabilizers.com/high-performance-active-fin-stabilizers-improve-boat-speed-performance/
ABSTRACTMany articles clearly state that the birth rate is expected to drop under the covid-19 pandemic. Based on the past study, after the Spanish flu pandemic there was a surge called, Spanish flu baby boom. The strength of economy after the pandemic determined the size of the surge.Meredith Wadman wrote a short article on the birth rate of the covid-19 pandemic1. Döring described a commentary article on how the covid-19 pandemic affecting our sexualities2. Miriam also mentioned how the covid-19 pandemic is affecting birthrates worldwide3. Brookings institution predicts the followings4:the covid-19 episode will likely lead to a large, lasting baby bust,the pandemic has thrust the country into an economic recession,economic reasoning and past evidence suggest that this will lead people to have fewer children,the decline in births could be on the order of 300,000 to 500,000 fewer births next year.All articles1,2,3,4clearly state that the birth rate is expected to drop under the covid-19 pandemic.We can sometimes learn from the past study. According to CDC on the Spanish flu pandemic (H1N1 virus), lasting from February 1918 to April 1920, it infected 500 million people–about a third of the world’s population at the time5. Over three waves of infections, the Spanish flu killed at least 50 million worldwide5. Based on the past study of the Spanish influenza pandemic, the birth rate was dropped during the pandemic6,7,8. After the pandemic there was a surge called, Spanish flu baby boom6,7,8. However, we don’t know when the covid-19 pandemic will be ended. The world population in 1918 was less than 2 billion while it is now nearly 7.8 billion. By the summer of 1919, the flu pandemic in US came to an end, as those that were infected either died or developed immunity9. We know the fact that the U.S. fertility rate is proportional to the strength of economy which can be generalized worldwide10. Based on the fact, the birth rate may be strongly influenced by the strength of economy after the pandemic. In other words, it will surge after the pandemic where the birth rate spike may be depending on the state of economy.This research did not receive any specific funding. The authors declare no conflict of interest.References:Meredith Wadman, COVID-19 unlikely to cause birth defects, but doctors await fall births, Science 07 Aug 2020: Vol. 369, Issue 6504, pp. 607Döring, N. How Is the COVID-19 Pandemic Affecting Our Sexualities? An Overview of the Current Media Narratives and Research Hypotheses.Arch Sex Behav (2020).https://doi.org/10.1007/s10508-020-01790-zMiriam Berger, Coronavirus baby boom or bust? How the pandemic is affecting birthrates worldwide, the Washington Post, July 15, 2020.https://www.washingtonpost.com/world/2020/07/15/coronavirus-baby-boom-or-bust-how-pandemic-is-affecting-birthrates-worldwide/4. Melissa S. Kearney and Phillip B. Levine, “Half a million fewer children? The coming COVID baby bust”, June 15 2020.https://www.brookings.edu/research/half-a-million-fewer-children-the-coming-covid-baby-bust/5.https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html6. https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/livebirths/articles/trendsinbirthsanddeathsoverthelastcentury/2015-07-157. Mamelund, Svenn-Erik. “Can the Spanish Influenza Pandemic of 1918 Explain the Baby Boom of 1920 in Neutral Norway?” Population (English Edition, 2002-) , vol. 59, no. 2, 2004, pp. 229–260.JSTOR ,www.jstor.org/stable/3654904.8. Siddharth Chandra et al., The 1918 influenza pandemic and subsequent birth deficit in Japan, DEMOGRAPHIC RESEARCH, vol.33, 11, pp. 313−326, 6 AUGUST 2015.9. Spanish flu, https://www.history.com/topics/world-war-i/1918-flu-pandemic10. Mark Mather, The Decline in U.S. Fertility, July 18, 2012. https://www.prb.org/us-fertility/
Many scientists have discussed what are reasonable or appropriate ecological and epidemiological models of covid-191,2,3. Their goal lies in that their models can be used for accurately predicting covid-19 spread. Of course, the models are useful, however they should be used in practice for reducing infection risks. The airflow or ventilation control plays a key role in alleviating the infectious diseases spread4. The new research was awarded to reduce infection risks for covid-195. We should use the latest cleanroom strategy for reducing infection risks. Instead of blowing air against human indoor, sucking air against human should be used in ventilation control for disturbing virus transmission to human6. A negative pressure room will play a key role in mitigating covid-19 pandemic by controlling the airflow to avoid covid-19 viruses against human bodies6.References:Carlson, C.J., Chipperfield, J.D., Benito, B.M. et al. Don’t gamble the COVID-19 response on ecological hypotheses. Nat Ecol Evol 4, 1155 (2020). https://doi.org/10.1038/s41559-020-1279-2Carlson, C. J., Chipperfield, J. D., Benito, B. M., Telford, R. J. & O’Hara, R. B. Nat. Ecol. Evol. 4 , 770–771 (2020)Araújo, M. B., Mestre, F. & Naimi, B. Nat. Ecol. Evol .https://doi.org/10.1038/s41559-020-1246-y(2020)Morawska, L., & Cao, J. (2020). Airborne transmission of SARS-CoV-2: The world should face the reality. Environment international ,139 , 105730.https://doi.org/10.1016/j.envint.2020.105730RAPID: Smart Ventilation Control May Reduce Infection Risk for COVID-19 in Public Buildings, 2020 https://www.nsf.gov/awardsearch/showAward?AWD_ID=2029690&HistoricalAwards=false Airborne InfectiousDisease ManagementMethods for Temporary Negative Pressure Isolation prepared by Minnesota Department of Health https://www.health.state.mn.us/communities/ep/surge/infectious/airbornenegative.pdf