In the Introduction (page 12), the author incorrectly characterizes positive feedback loops as “virtuous” and negative feedback loops as “vicious.”  For a negative feedback loop, the author provides the example of bad news causing a stock’s price to decline thereby causing more bad news thereby causing the stock’s price to decline further.  It is obvious that the author thinks this is a negative feedback loop because the stock’s price is heading in a negative direction.  In fact, (this stage of) the cycle described is a positive feedback loop, since the bad news causes more decline of the stock’s price and the decline of the stock’s price causes more bad news.  The changes increase each other in a vicious, destabilizing cycle.  I say “this stage of” the cycle because eventually the stock’s price will decline to a point where the number of buyers actually increases (good news).  So, the determination as to whether a system is experiencing positive (vicious, destabilizing) feedback or negative (virtuous, stabilizing) feedback depends on the time period during which the system is observed as well as on which inputs and outputs are observed.

A Ponzi scheme is a good example of a positive feedback loop.  The excellent results experienced by the early participants lead to more participants which leads to more excellent results.  Unfortunately, the continuation of such a scheme requires an infinite pool of potential participants.  There is no virtuous mechanism to stabilize the system and eventually there are too few new participants to pay off the earlier participants and the scheme collapses.  Viral expansion is not a good example of a positive feedback loop and in fact any system that exhibits a sigmoid (S-shaped) growth curve is not an example of a positive feedback loop.

In Chapter 11 (page 206), we learn that the founders of Facebook were “tacking up on their walls pictures of S curves representing the adoption rates on various campuses.”  Clearly the founders of Facebook were aware that the adoption rate was subject to a negative feedback loop.  The adoption rate increased at an increasing rate up to a point after which the adoption rate increased at a decreasing rate.  The point at which growth begins increasing at a decreasing rate is the inflection point.  On page 206, the author says, “The bigger the school, the longer it took to arrive at full inflection.  At Cornell a couple of weeks passed before exponential growth kicked in.”  I’m not sure the author knows what he means there.  I’m guessing that if you looked at the figures you’d find that exponential growth at Cornell began immediately and that it took a couple weeks until a limiting factor kicked in, resulting in an inflection point after which the growth rate was ameliorated.  Remember the example given in the Introduction:  doubling a penny every day for thirty days.  By the end of one week, you’d only have 64 cents, but the amount of money you have is (and has been since Day 1) growing exponentially.

I’m going to keep reading this book, but I’ll be wondering about the actual level of truth in everything the author says.

Lindsey Vonn’s workout

Apolo Ohno’s workout

“From manga and anime to movies, magazines, video games, advertising and music, Japanese schoolgirls are everywhere. For years, schoolgirls have shown up in internationally popular anime such as Sailor Moon, The Melancholy of Haruhi Suzumiya, and Blood: The Last Vampire. Films such as Battle Royale inspired Quentin Tarantino to include a fighting schoolgirl in Kill Bill; and recently, Rinko Kikuchi received an Oscar nomination for her role as a schoolgirl in the film Babel. There are schoolgirl characters in video games such as Street Fighter. And the “Japanese Schoolgirl Watch” column in Wired magazine has long kept an eye on the trends emerging among these stylish teens. In effect, the Japanese schoolgirl has all but replaced the “geisha -girl” as Japan’s new female icon.”

from Wired magazine, April 2003:

“With the cut, color, and brand of clothing, shoes, and book bags dictated by school dress codes, hipsters have to think small. Very small. As in designer logos on their socks. In uniformed classrooms, knee-highs must be navy blue, black, or white, yet all but the most conservative faculties allow small insignias just below the knee. Logo socks, priced at around 1,000 yen ($8.50), are an inexpensive way to stand out. ‘They don’t have to be designer logos if they’re really cute, like flying hearts. But,’ warns student Makika Sudo, ‘the socks have to be ribbed, not smooth.’”

“…What I think is, it’s never
too late…or, in my case, too
early, to be whoever you want to
be…There’s no time limit, start
anytime you want…change or stay
the same…there aren’t any
rules…We can make the best or
worst of it…I hope you make the
best…I hope you see things that
startle you. Feel things you
never felt before. I hope you
meet people who have a different
point of view. I hope you
challenge yourself. I hope you
stumble, and pick yourself up. I
hope you live the life you wanted
to…and if you haven’t, I hope
you start all over again.”

Today, I used the new e-mail address to test the FindByEmail service described in the January 16 post on petewarden.typepad.com.  I was surprised to find that the new e-mail address was listed under “aim” on the resulting test page.

How would AIM know about my new e-mail address?

Taken with a 55-200mm zoom lens, set at 200mm, through a 60mm lens handheld backwards against the zoom lens.

The song title translates as “Long Live Life” and is taken from a painting by 20th century Mexican artist Frida Kahlo. The same artist whose eyebrows were the topic of conversation between my wife and daughter just the other day.  Coincidence?  You decide.

Viva la Vida

I used to rule the world
Seas would rise when I gave the word
Now in the morning I sleep alone
Sweep the streets I used to own

I used to roll the dice
Feel the fear in my enemy’s eyes
Listen as the crowd would sing:
“Now the old king is dead!
Long live the king!”

One minute I held the key
Next the walls were closed on me
And I discovered that my castles stand
Upon pillars of salt and pillars of sand

I hear Jerusalem bells a ringing
Roman Cavalry choirs are singing
Be my mirror my sword and shield
My missionaries in a foreign field
For some reason I can’t explain
Once you go there was never, never an honest word
That was when I ruled the world
(Ohhh)

It was the wicked and wild wind
Blew down the doors to let me in
Shattered windows and the sound of drums
People couldn’t believe what I’d become

Revolutionaries wait
For my head on a silver plate
Just a puppet on a lonely string
Oh who would ever want to be king?

I hear Jerusalem bells a ringing
Roman Cavalry choirs are singing
Be my mirror my sword and shield
My missionaries in a foreign field
For some reason I can’t explain
I know Saint Peter will call my name
Never an honest word
But that was when I ruled the world
(Ohhhhh Ohhh Ohhh)

I hear Jerusalem bells a ringing
Roman Cavalry choirs are singing
Be my mirror my sword and shield
My missionaries in a foreign field
For some reason I can’t explain
I know Saint Peter will call my name
Never an honest word
But that was when I ruled the world
Oooooh Oooooh Oooooh

In case you’re still wondering about those eyebrows, here is one of Frida Kahlo’s self-portraits: