Dee

Art Life: poetry, songs, maxims, illustrations

[Dee @DeonStreit]

@WaywardRabbler They killed a handful of policemen in doing so, using several bombs. But all the bills were marked and couldn't be spent.

[Dee @DeonStreit]

@pwrhungry Vaclav Smil in "Energy and Civilization" [2017] wrote that the use of coal would almost certainly expand until 2050 as other countries attempt to modernize and expand their infrastructure.

[Dee @DeonStreit]

@owenbroadcast Women can be tetrachromatic, especially perceptive amongst shades of red, while men may be colorblind.

This ia because a gene necessary for perception of color is on the X chromosome, of which women (XX) have 2.

[Gaurab Chakrabarti @Gaurab]

Boeing pumps nitrogen into every 787 Dreamliner wing. Not for pressure. To prevent explosions. It is called OBIGGS. Cabin air is forced through hollow fiber membranes at high pressure. Oxygen slips through the membrane walls faster than nitrogen. The nitrogen-enriched air fills the fuel tank ullage space as fuel is burned. Below 12% oxygen, jet fuel vapor cannot ignite. The 787 was the first commercial aircraft to inert all wing fuel tanks continuously from takeoff to landing. TWA Flight 800 exploded in 1996 when fuel vapors in the center wing tank ignited. 230 people died. The FAA mandated fuel tank inerting for all new aircraft in 2008. Boeing solved it with a membrane thinner than a sheet of paper and a gas that makes up 78% of the air you are breathing right now.

[Dee @DeonStreit]

@sivori TS Eliot - Four Quartets

[Dee @DeonStreit]

@QuetzalPhoenix "Narcissism of small differences"

https://t.co/h9CACvQ49A

[Benjamin Morris @skepticalsports]

That chances of a 1/n event happening in n tries converges quickly on 63% (1-1/e to be exact) has been one of my favorite useful real world math shortcuts since high school.

[Dee @DeonStreit]

@vashikoo Deakins was Oscar nominated twice that year for best Cinematographer... and didn't win either.
His other film: No Country for Old Men

[Dee @DeonStreit]

@hkozachkov A poem I wrote 15 years ago, of which your prompt reminded me

[Alec Helbling @alec_helbling]

Stokes' Theorem is a classic result from vector calculus.

It tells us that the line integral of a vector field over a loop is equal to the surface integral of the curl of the vector field over some enclosed surface.

[Dee @DeonStreit]

Selected #books I've read in 2025:

An Immense World - @edyong209
Blindsight -Peter Watts
Man from the Future - @Ananyo
Over Ruled -Neil Gorsuch
In the Presence of Absence -Darwish
Visual Display of Quantitative Info - @EdwardTufte
How to Listen When Markets Speak - @Convertbond

[Sahil @sahilypatel]

The deeper you go into the semiconductor supply chain, the less believable it becomes.

> TSMC, a company on a small island, produces over 90% of the world’s most advanced chips
> TSMC relies on dutch company ASML for EUV lithography machines
> ASML depends on German Company Carl Zeiss, the only firm in the world capable of making mirrors precise enough for ASML’s requirements.
> The light source for ASML’s EUV machines is produced by a single company in San Diego.
> The photoresists used to print transistor patterns are produced by Japanese firms like JSR and Tokyo Ohka Kogyo.
> The ultra-pure quartz needed to make silicon wafers comes entirely from a single mine in Spruce Pine, North Carolina.
> The copper and rare-earth materials inside chips are mined and refined across Chile, the Congo, and China.
> The specialized gases used in chipmaking, like neon and fluorine, largely come from Ukraine and Japan.
> The design blueprints for these chips often come from American companies like NVIDIA, AMD, and Apple, which rely on software tools from U.S. firms like Synopsys and Cadence.

Remove any single piece and the whole system collapses.

[Andrew Côté @Andercot]

The first thing to understand is this:

A bolt is a spring. It applies force by being stretched.

That means it needs to stay within the linear elastic regime of the stress-strain diagram.

"wow" you think. "I never knew that." Of course you didn't. Its not even 1% of bolt-physics.

[Niko McCarty. @NikoMcCarty]

A single aquaporin protein lets one billion water molecules into a cell each second. It is one of the "fastest" channels in all of biology.

Each water flows through in single file, while H+, sodium, potassium, and other ions are excluded.

What explains this remarkable selectivity? Two clever protein filters.

But first: Each aquaporin protein is made from six alpha-helices that run back and forth through the cell membrane. These helices form an hourglass shape so that the channel is cone-shaped at either end and extremely narrow in the middle.

The two ends of the protein also mirror each other, with their point of symmetry occurring at the narrowest part of the channel. It's thought that modern aquaporins evolved through a gene duplication event.

Now let's zoom in a bit and look at the two filters within aquaporin that account for its extreme selectivity. Water can flow either way through the channel, so we'll imagine that we're moving from OUTSIDE the cell to INSIDE the cell.

The first filter we encounter is called the ar/R filter. This is a cluster of polar and charged amino acids that point inside the aquaporin channel.

These four amino acids are *usually* arginine (+ charge), histidine (polar), and two bulky amino acids like phenylalanine and tryptophan.

These four amino acids come together to restrict the middle of the pore, making it just wide enough for a single water molecule to pass. The positively charged arginine also helps "stabilize" water molecules while forcing away sodium ions or protons.

The second filter encountered on our journey into the cell is called the NPA motif (short for asparagine–proline–alanine). There are two of them inside each aquaporin.

These two protein motifs point at each other in the center of the aquaporin. As a water molecule passes the ar/R filter and moves deeper into the channel, it forms hydrogen bonds with the asparagine amino acid in the first NPA motif.

But because the two motifs are oriented in opposite directions, the local electric field at the channel’s midpoint next forces each water molecule to rotate 180° and latch onto the asparagine in the second NPA motif. In other words, each water molecule gets flipped around inside the aquaporin channel.

This "flipping" is important because it breaks the water molecules free from any hitch-hiking protons. It acts as the final filter.

[Dee @DeonStreit]

Replication crisis in my memes

[Dee @DeonStreit]

@mattparlmer in Vaclav Smil's book "Growth" he writes that natural constraints make any exponential growth rate become sigmoid (if I recall correctly)

[Dee @DeonStreit]

@mattduss Samantha Power, before she was a politician, wrote a book called "A Problem from Hell: America and the Age of Genocide" (2002). It won the Pulitzer.

[Dee @DeonStreit]

@cremieuxrecueil https://t.co/56tLIkXbgB

[Tivadar Danka @TivadarDanka]

In calculus, going from a single variable to millions of variables is hard.

Understanding the three main types of functions helps make sense of multivariable calculus.

Surprisingly, they share a deep connection. Let's see why!