TIL that you can use matrix notation and linear algebra to study conic sections.

Ref:- https://en.wikipedia.org/wiki/Matrix_representation_of_conic_sections

TIL that Grab designed a special camera called KartaCam in order to build their own maps in Southeast Asia. The camera is mounted on the motorbikes of their delivery drivers. The collected data is then added to OpenStreetMap.

Ref:- https://restofworld.org/2024/grab-google-maps-southeast-asia/

TIL that ~20% of the fresh water on Earth's surface is in a single lake called Lake Baikal.

Ref:- https://www.britannica.com/place/Lake-Baikal

TIL that when UAE was becoming a country in 1971, its founders went village to village, tribe to tribe, asking each which ruling family they were loyal to. Then that's where they drew the boundaries between states.

Ref: https://sive.rs/dxb

TIL that the Japanese have a system called Koseki where all the personal and family details are recorded.

Ref: https://en.wikipedia.org/wiki/Koseki

TIL that factories in India with over 100 employees require government permission to fire workers.

Ref: https://www.wsj.com/world/asia/to-challenge-china-india-needs-to-get-out-of-the-way-of-its-factory-owners-28cb4a6f

TIL about Pyrosomes. They are free-floating colonial tunicates that live in the ocean. They are bioluninescent. Here is a nice video on them https://www.youtube.com/watch?v=qis_rfb7fnU .

TIL: “Kentucky windage” refers to the practice of holding the aim to the upwind side of the target (also known as deflection shooting or “leading” the wind) to compensate for wind drift, without actually changing the existing adjustment settings on the gunsight.

Ref: https://en.wikipedia.org/wiki/Windage#Ballistics → 2nd paragraph

TIL: The 'IN' in the output of 'dig' command is the “query class” and stands for “internet”. It is basically a relic from the 80s and 90s when there were other networks competing with the internet like “chaosnet”.

Ref: https://jvns.ca/blog/2021/12/04/how-to-use-dig/

TIL: The risk of down syndrome increases with maternal age.

Ref: https://www.floridahealth.gov/diseases-and-conditions/birth-defects/_documents/Data_Report/_documents/Maternal_Age_and_Down_Syndrome.pdf

Qanat is an ancient system of water supply which allows water to be transported over long distances in hot dry climates without loss of much of the water to evaporation. Here is a fascinating video on it.

• https://www.youtube.com/watch?v=vH3crh44GQ4 - Qanat in Iran

A polyester textile is the same PET material (polyethylene terephthalate) as a plastic soda bottle, only extruded into a filament rather than molded into a container. Like the bottle, the fiber repels water. It’s hydrophobic.

https://worksinprogress.co/issue/how-polyester-bounced-back/

There is a special aircraft called “Airbus BelugaXL” which is used to transport very large aircraft components, such as aircraft wings.

https://en.wikipedia.org/wiki/Airbus_BelugaXL

There used to be an anti obesity drug called fen-phen back in the 90s that was initially FDA approved but later found to cause heart valve abnormality and was then taken off the market.

Ref:

• https://www.nytimes.com/1997/09/23/science/how-fen-phen-a-diet-miracle-rose-and-fell.html
• https://en.wikipedia.org/wiki/Fenfluramine/phentermine

Google’s ‘Project Nightingale’ gathers personal health data on millions of Americans

Ref:

• https://www.wsj.com/articles/google-s-secret-project-nightingale-gathers-personal-health-data-on-millions-of-americans-11573496790
• https://en.wikipedia.org/wiki/Project_Nightingale

There is a rule called “business judgement rule” which protects the Board of Directors from personal civil liability when they make business decisions for a company.

Ref: https://www.investopedia.com/terms/b/businessjudgmentrule.asp

If you are going out of town for an extended period of time, you can ask USPS to hold your mail until you return by putting a “hold mail” request on their website.

More info at https://www.usps.com/manage/hold-mail.htm

The pressure at the bottom of the Mariana Trench is ~1000 times more than the pressure at the sea level. Even at these levels, the density of water goes up by just ~5%.

I knew water is an incompressible fluid. But did not realize how hard it is to compress it!

See also:

• https://en.wikipedia.org/wiki/Mariana_Trench → 2nd paragraph.
• https://physics.nmu.edu/~ddonovan/classes/Nph201/Homework/CHFLD/CHFLDP09.pdf - shows that an underwater vehicle's observation window at the bottom of the Mariana Trench will experience forces on the order of the weight of a jetliner.

• Caesar salad originated from Tijuana, Mexico.
  • https://en.wikipedia.org/wiki/Caesar_salad

• There are two ways to write the numbers in Chinese and Japanese. One is used in everyday writing and the other is used in commercial, accounting or financial contexts. The latter have more strokes and so can't be forged. For example, the number 1 is normally written as 一 but in commercial records it is written as 壹.

Ref:

• [1] https://en.wikipedia.org/wiki/Chinese_numerals#Ordinary_numerals
• [2] https://en.wikipedia.org/wiki/Japanese_numerals#Formal_numbers

• An ij in Dutch is pronounced as <ay> in “pay”. For example, Dijkstra in “Edsger Dijkstra” is pronounced as daykstra.

Ref:

• [1] https://en.wikipedia.org/wiki/IJ_(digraph)
• [2] https://en.wikipedia.org/wiki/Edsger_W._Dijkstra - has an audio file that shows how to say the name.

• The trailing 'i' in a Roman numeral used to be written as a 'j' . For example 1, 2, 3, 6, 7, and 8 are rendered as j, ij, iij, vj, vij, and viij. This is (1) to make it clear that the number has ended and (2) to make it harder to alter the numeral by adding more i's on the end.

Ref:

• [1] https://genealogy.stackexchange.com/questions/3748/what-is-the-significance-of-the-character-j-at-the-end-of-a-roman-numeral
• [2] https://blog.plover.com/2024/06/23/#script-potpourri

• There is a fruit called Durian (https://www.google.com/search?q=durian+fruit&tbm=isch). It looks similar to jack fruit but is an unrelated species (https://en.wikipedia.org/wiki/Durian). It is in huge demand in China (https://www.nytimes.com/2024/06/16/business/durian-china-malaysia-thailand.html).

• The frequency illusion (also known as the Baader–Meinhof phenomenon) is a cognitive bias in which a person notices a specific concept, word, or product more frequently after recently becoming aware of it.
  • Ref:- https://en.wikipedia.org/wiki/Frequency_illusion

• pandas has a resample function (https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.resample.html) to change the frequency of timeseries. For example, let's say you have daily OHLC (open, high, low, close) data of a stock. You can use this function to convert it to monthly OHLC data. Very convenient!

• Shatapawali is a Marathi term which refers to an age-long Indian custom of taking a stroll after a meal.
  • https://en.wikipedia.org/wiki/Shatapawali
    • Walking at least 100 steps after lunch or dinner improves overall wellbeing.

TIL: An earworm is a song that you keep hearing in your head

Ref: https://dictionary.cambridge.org/us/dictionary/english/earworm

TIL: In order to be listed on Nasdaq, companies need to have a woman, “underrepresented minority” or “LGBTQ+” member in their board - or publicly explain why they don’t. If it is a big company, they require two such candidates.

Ref: https://www.wsj.com/articles/texas-stock-exchange-txse-new-york-blackrock-citadel-securities-james-lee-bb72c36c?mod=hp_opin_pos_1

• Octopuses have 3 hearts, 9 brains, and blue blood.
  • https://apnews.com/article/ba6e3fa5bb804565b9d6d666b6d40a73

• https://app.diagrams.net/ can be used to make application architecture diagrams. It is similar to Microsoft Visio but free.
• https://github.com/jgraph/drawio - the source code for https://app.diagrams.net
• https://excalidraw.com/ - sketch diagrams that have a hand-drawn feel to them
• https://github.com/excalidraw/excalidraw - the source code for https://excalidraw.com

• What is commonly referred to as “football” in the world, is called as “soccer” in America. But it is actually the English that started calling it that.
  • https://www.britannica.com/story/why-do-some-people-call-football-soccer