Monthly Archives: June 2008

Aging with grace

Bill’s comment on my previous post reminded me of a book I read a few years ago, Aging With Grace by David Snowdon. The author describes what he learned about aging and especially about Alzheimer’s disease by studying a community

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Brain plasticity

Today’s Big Ideas podcast carried a lecture by Norman Doidge on neuroplasticity, the recently-discovered ability of the brain to rewire itself. Doidge relates several amazing stories of people who have recovered from severe strokes or other brain injuries by developing detours around the

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Posted in Science

Tips for using regular expressions

Jeff Atwood just posted a good article on regular expressions. Not the syntax of regular expressions but rather the strategy of when and how to use them.

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Posted in Software development

Wine, Beer, and Statistics

William Gosset discovered the t-distribution while working for the Guinness brewing company. Because his employer prevented employees from publishing papers, Gosset published his research under the pseudonym Student. That’s why his distribution is often called Student’s t-distribution. This story is fairly well

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Posted in Statistics

Two definitions of expectation

In an introductory probability class, the expected value of a random variable X is defined as where fX is the probability density function of X. I’ll call this the analytical definition. In a more advanced class the expected value of

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Posted in Math

Why computer scientists count from zero

In my previous post, cohort assignments in clinical trials, I mentioned in passing how you could calculate cohort numbers from accrual numbers if the world were simpler than it really is. Suppose you want to treat patients in groups of 3.

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Posted in Software development

Cohort assignments in clinical trials

Cohorts are very simple in theory but messy in practice. In a clinical trial, a cohort is a group of patients who receive the same treatment. For example, in dose-finding trials, it is very common to treat patients in groups of

Posted in Clinical trials

Monitoring legacy code that fails silently

Clift Norris and I just posted an article on CodeProject entitled Monitoring Unreliable Scheduled Tasks about some software Clift wrote to resolve problems we had calling some legacy software that would fail silently. His software adds from the outside monitoring and

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Posted in PowerShell

Fasting may reduce chemotherapy side-effects

Chemotherapy harms cancer cells as well as normal cells. Chemotherapy is designed to be more harmful to cancer cells than to normal cells, but the damage to normal cells can be brutal. New studies suggest that fasting prior to receiving

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Saving energy by tolerating mistakes

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

Posted in Computing

Why functional programming hasn't taken off

Bjarne Stroustrup made a comment in an interview about functional programming. He said advocates of functional programming have been in charge of computer science departments for 30 years now, and yet functional programming has hardly been used outside academia. Maybe

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Posted in Software development

Probability approximations

When I took my first probability course, it seemed like there were an infinite number of approximation theorems to learn, all mysterious. Looking back, there were probably only two or three, and they don’t need to be mysterious. For example,

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Attention span by nationality

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.

Posted in Uncategorized

What makes the Mentos-Diet Coke trick work

The American Journal of Physics has an article in the June issue about the physics of dropping Mentos into Diet Coke. The spectacular result depends on physical characteristics of the Mentos, not their chemical composition. Here’s an explanation from the

Posted in Science

Bugs in food and software

What is an acceptable probability of finding bug parts in a box of cereal? You can’t say zero. As the acceptable probability goes to zero, the price of a box of cereal goes to infinity. In practice, the FDA sets

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Posted in Software development, Statistics