6 Months of guerilla CO2 measurement with the COVID CO2 tracker

•August 10, 2021 • Leave a Comment

It’s been six months since I started work on an app to crowdsource CO2 measurements as a COVID mitigation effort. Volunteers (“CO2 guerillas”) across the world have since added nearly 600 measurements to the database, as part of an effort to document safe and dangerous indoor spaces.

The app (deployed at: https://covid-co2-tracker.herokuapp.com/home) was born out of the need to improve indoor air quality in the middle of a highly contagious airborne respiratory pandemic. Somehow – more than a year into this – governments around the world deny the very fact that this virus is spread through the air, not through surfaces and “droplets”. This was obvious from the very beginning to me, and to hundreds of aerosol scientists, safety engineers, HVAC specialists, and even entire countries where SARS-1 epidemics hit in the past.

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React internals: Fibers

•August 22, 2019 • Comments Off on React internals: Fibers

If you’ve ever worked with a complex framework like React, you might know that there’s a LOT going on behind the scenes to make everything work. Libraries like boost are infamous for their complexity, and the complex programming responsible for their useful features.

React, a javascript library for building entire frontend web apps, has the same complexity. It maintains an entire emulated DOM (to attempt reduction in browser-side re-rendering), extensions to Javascript (JSX, for embedded pseudo-html syntax), state management (to update the UI by comparing the emulated DOM with updates), and insanely complex backends for implementing everything uniformly.

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Functional Programming vs Object Oriented Programming

•August 14, 2019 • Leave a Comment

Written by myself, Tomas Engquist, and Harpreet Ghotra. They each did more than their share of the work!

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querySelector vs getElementByID

•August 1, 2019 • Leave a Comment

A quirk of modern Javascript is that we have (at least) two ways of programmatically finding items in the DOM. querySelector is the newer of the two, dating to 2013, and is the more powerful one. It has a fancy syntax, and lets us write complex queries for groups of elements, classes, and subelements. But more powerful isn’t always more betterer.

It turns out that the added complexity means getElementByID is about twice as fast as querySelector. They’re both pretty fast, but I’m going to look into why getElementByID is faster.

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Processing audio in the browser!

•July 18, 2019 • Leave a Comment

The modern web is an amazing place. You can do almost anything in a browser that you can do in native code. Including processing audio in realtime. In javascript.

Nuts? Probably. Worth it? Definitely.

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Ruby on Rails testing goes parallel – a deep dive!

•July 2, 2019 • Leave a Comment

If you ever work on large software projects, you’re bound to spend a LOT of time compiling code, running unit tests, and lots of other non-code stuff.


Since programming is really thought-intensive, any focus breaks are really disruptive. Even a ten second test suite is enough to break a train of thought. What can we do to improve that? Parallelize it of course!


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Diagnosing Ruby require_relative issues with DTrace on OSX

•June 20, 2019 • Leave a Comment

Ruby, like many programming languages, has a C-like mechanism for using code defined in other files. It’s critical for the development of any serious program, but it’s also prone to weird errors when files aren’t included in the proper order, or not included at all. It’s usually pretty obvious which file you’re not require_relativeing, but there are times when the only way to make sense of things is to trace the system calls.

On Windows, Process Monitor is by far the best way to diagnose this sort of problem. It gives a useful trace of just about everything a process does. I’ve used it many times before to diagnose file loading issues, and weird compiler errors. Similarly, strace on Linux traces every system call.

But what about OSX?

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Extreme Heat Event in Northern Siberia and the coastal Arctic Ocean This Week

•July 6, 2018 • Leave a Comment

This global warming stuff is getting to be really quite scary. 😫

Monday’s eclipse & The Fight of The Century

•August 19, 2017 • Leave a Comment

On Monday March 8, 1971, Joe Frazier fought Muhammad Ali in “The Fight of The Century”. It was an event that was so popular that The Citizen’s Commission to Investigate the FBI used it to break into an FBI office and steal every file.

On Monday, a solar eclipse will cross the United States, with the zone of totality crossing from Washington to South Carolina. With millions of Americans stopping what they’re doing to look up at the sun for a few minutes – not quite as long as a boxing match – who knows what people will do?

Wheelbarrows of Money

•May 9, 2016 • Leave a Comment

The idea of just “printing money” to pay off the US Federal government debt is back in the news. Here’s a reminder of what that entails.

Keri M. Peardon

After reading my post about the “Depression Pocketbook,” my husband asked if I actually had any verifiable proof that anyone in Germany (or anywhere else) bought bread (or anything else) with a wheelbarrow full of money. It’s something we’ve both heard people say, but I must admit, I couldn’t quote a source.

Is it an urban legend? Is it something historians have invented because it sounds good? God knows when I was in school, I was told medieval people believed the world was flat. Not only was that never true (and there’s evidence from their maps and writings to prove it), but the idea can actually be traced back to a writer (I believe it was Nathaniel Hawthorne) who first used it in his popular biography of Christopher Columbus. It was taken for truth and repeated until it became reality and the truth became lost.

Is that what…

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