The blog of John D. Cook
From the category archives:
To balance my previous post about a bad user interface design, here’s an example of a good user interface design from Tom Peters. TP gushes over the design of his EpiPen, a device that lets users self-administer Epinephrine to prevent anaphylactic shock from an allergic reaction.
The device is easy to use, comes with a good manual, and has a practice mode with feedback.
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Every time I get into a hotel shower I think “Oh great. How does this one work?” No two are the same, and yet I’ve never seen a shower that had the simplicity and convenience of the typical residential shower with two knobs, one for hot water and one for cold. (At least that’s what’s most common in the US.)
Here’s how the shower was labeled in my hotel in Denver this week:
I assumed that the off position was at 4 o’clock, the hottest water at 3 o’clock, and the coldest at 9 o’clock. So I turned the handle to the 2 o’clock position and waited for the water to warm up. Eventually I realized the shower should have been labeled something like this:
The original label was misleading in two ways. First, it implied that you get warmer water by turning the handle clockwise. Second, it implied that the range of motion of the handle was between 9 o’clock and 4 o’clock. But to get a warm shower you have to turn the knob counterclockwise to between 5 and 6 o’clock.
Why do hotel shower designers go to great lengths to frustrate users? What’s wrong with simply having hot and a cold water knobs? Would this add a few dollars to the construction cost of a room? If so, I could think of a long list of ways I’d rather they cut costs. Are they concerned about guests who don’t know English? If so, then why assume that guests know what the letters “C” and “H” stand for? How about pictures of penguins and ice cubes drawn in blue above the cold water knob, and pictures of boiling water and fire drawn in red above the hot water knob?
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Check out this article from The Technium estimating the amount of labor, 40% of which has been unpaid, to create the content currently on the web.
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My previous post listed seven things that cause new brain cells to grow, taken from a talk by Dean Ornish. Here’s the corresponding list from the same talk of things that decrease brain cells.
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Dr. Dean Ornish gave an inspiring three-minute talk at TED entitled Your genes are not your fate. As part of his talk he lists six things that cause new brain cells to grow:
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I use LaTeX for math documents and PowerPoint for presentations. When I need to make a math presentation, I can’t have everything I want in one environment. I usually go with PowerPoint.
Yesterday I tried the LaTeX Beamer package based on a friend’s recommendation. I believe I’ll switch to using this package as my default for math presentations. Here are my notes on my experience with Beamer.
Installation
Beamer is available from SourceForge. The installation instructions begin by saying “Put all files somewhere where TeX can find them.” This made me think Beamer would be another undocumented software package, but just a few words later the instructions point to a 224-page PDF manual with plenty of detail. However, I would recommend a couple minor corrections to the documentation.
latex-beamer, pgf, and xcolor. The Package Manager shows no latex-beamer package, but does show a beamer package.The installation went smoothly overall.
Using Beamer
I found Bruce Byfield’s introduction to Beamer helpful. The Beamer package is simple to use and well documented.
It’s nice to use real math typography rather than using PowerPoint hacks or pasting in LaTeX output as images. I also like animating bullet points simply by adding \pause to the end of an enumerated item.
Inserting images
The biggest advantage that PowerPoint has over LaTeX is working with images. With PowerPoint you can:
The last point may not seem like much until you’ve tried to figure out how to include images in LaTeX.
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Yesterday I added a blog to the ReproducibleResearch.org web site. You can visit the site here or subscribe via RSS.
I’d like a couple people to join me in writing this blog, and I would greatly appreciate suggestions, guest posts, etc. If you’re interested, please send a note to contribute at the domain name.
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Computerworld has a good article on why electronic medical records are so slow to appear. Many people I’ve talked to believe that medical data is just harder to work with than other kinds of data. They see the barriers to electronic medical records as primarily technical. That’s hard to swallow when nearly every other sector of the economy has electronic records. As the Computerworld article says, we’ve had the technology to pull this off for 30 years. There are more plausible economic explanations for why EMRs are uncommon. In a nutshell, the party that pays to develop an EMR is not the party that reaps most of the financial benefit so there’s little incentive to move forward.
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From time to time people speculate whether Einstein was an atheist. Richard Dawkins, for example, said in his book The God Delusion that Einstein was an atheist. However, Einstein addressed this point directly:
I am not an atheist, and I don’t think I can call myself a pantheist.
This quote comes from There Is a God by Anthony Flew. Flew in turn credits Max Jammer’s book Einstein and Religion, page 44.
For sixty years Anthony Flew was an apologist for atheism. Four years ago he announced that he had changed is mind. Last year he published There Is a God, an account of how he first became an atheist and of how decades later he reversed his position.
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The latest Pixel8 podcast has an interview with world-class debugger and former Green Beret John Robbins.
John Robbins is a terrific speaker and author. In the podcast interview he gives some background on how he became an expert troubleshooter. He and shares some war stories of how he saved companies from bankruptcy by finding the bug no one else could find and gives some general debugging advice.
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CaringBridge offers “free, personalized websites that support and connect loved ones during critical illness, treatment and recovery.” The site is sponsored by donors, not advertising.
When he was diagnosed with cancer four years ago, a friend of mine set up a password-protected web page to let us know the latest updates on his treatment and diagnosis. I appreciated his doing this. He could easily set up his own site, but not everyone knows how to do that. CaringBridge lets people who are not as technically inclined set up their own site. Patients can upload photos, exchange messages with friends, etc. About 100,000 families have set up web sites through CaringBridge so far.
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I ran across the book Team Moon by Catherine Thimmesh when I took my kids to the library. The book’s subtitle is “How 400,000 People Landed Apollo 11 on the Moon.” This children’s book focuses on the thousands of people who worked behind the scenes of Apollo 11. It highlights some of the things that went wrong or could have gone wrong. One of the early pages of the book quotes the speech that was prepared for President Nixon to read if the mission had failed.
Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace … These brave men, Neil Armstrong and [Buzz] Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice.
Grim words for a children’s book. And yet without some explanation of the dangers they faced, it’s impossible to appreciate the astronauts’ bravery. When I was a child, I was puzzled by talk of brave astronauts. In my mind, astronauts simply got on board a rocket the same way I got in a car. What was brave about that? It didn’t occur to me that they might not return safely.
Team Moon reminded me of Undaunted Courage by Stephen Ambrose. The image of the Lewis and Clark expedition I had from childhood was about as naive as my image of astronauts. I pictured a couple men with coonskin hats in a canoe going on a little trip, not 33 soldiers on a three-year mission. (The name “Lewis and Clark” doesn’t help, implying that they were the expedition rather than the leaders of the expedition.) I didn’t appreciate the scope or danger of the voyage until I read Ambrose’s book as an adult. I hope someone writes a children’s book in the style of Team Moon about the expedition if there’s not already such a book.
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Computer chips can use significantly less energy if they don’t have to be correct all the time. That’s the idea behind PCMOS — probabilistic complementary metal-oxide semiconductor technology. Here’s an excerpt from Technology Review’s article on PCMOS.
[Inventor Krishna] Palem’s idea is to lower the operating voltage of parts of a chip—specifically, the logic circuits that calculate the least significant bits, such as the 3 in the number 21,693. The resulting decrease in signal-to-noise ratio means those circuits would occasionally arrive at the wrong answer, but engineers can calculate the probability of getting the right answer for any specific voltage. “Relaxing the probability of correctness even a little bit can produce significant savings in energy,” Palem says.
In applications such as video processing, a small probability of error would not make a noticeable difference. It would an interesting exercise to separate those parts of a system that require accuracy and those that tolerate error. For example, a cell phone might use high-accuracy chips for dialing phone numbers but low-accuracy chips for controlling the display in order to extend battery life.
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The Code Wizard blog posted some anecdotal evidence of attention span varying as a function of nationality.
The author looked through the visitor statistics on his blog and observed that Americans spend less time per page than visitors from other countries. Visitors from Canada, Australia, and England spend far more time per page and click more links while they’re there. I’m not aware of anything in the content of the blog that would be intrinsically more interesting to folks outside the US.
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It’s not hard to use Greek letters and math symbols in (X)HTML, but apparently it’s not common knowledge either. Many pages insert little image files every time they need a special character. Such web pages look a little like ransom notes with letters cut from multiple sources. Sometimes this is necessary but often it can be avoided.
I’ve posted a couple pages on using Greek letters and math symbols in HTML, XML, XHTML, TeX, and Unicode. I included TeX because it’s the lingua franca for math typography, and I included Unicode because the X(HT)ML representation of symbols is closely related to Unicode.
The notes give charts for encoding Greek letters and some of the most common math symbols. They explain how HTML and XHTML differ in this context and also discuss browser compatibility issues.
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