Archive for February, 2008

IT security policy “research”

“Researchers find way to steal encrypted data,” screams this article in the New York Times.

Oh do they? But come… on…, what is this ridiculous demonstration? Okay, okay, it’s the IT Policy School over there, let’s cut them some slack. What they’ve come up with is a way to read seated DRAM under OS lock without specialized hardware, and if they said that, it would be fine.
(Read the article)

the Reuters jingle

Reuters likes to stick their three-chord jingle at the beginning and end of every one of their video clips on the net. It actually sounds a bit more interesting than the simple three-note jingles of major US TV networks like NBC. So I parsed it. Reuters jingle.

Input: \new PianoStaff <<
\new Staff
\relative c' {
\key e \major
\clef treble
<gis' cis>16 <b dis> <cis e>8 }
\new Staff
\relative c {
\key e \major
\clef bass
cis,16 gis' cis8 }

Polya’s urn, martingale, CLT

A problem described here

what do you expect to happen if you had 2 urns with a ball in each one…. and you placed balls in them…. choosing an urn with a probability proportional to the number of balls in each urn…..

intuitively, you’d expect a rich getting richer kind of thing….. or those with more balls getting even ballsier…. [see extreme sports.... those ppl are crazy... and get crazier] but the amazing thing is that you get a uniform distribution….. it’s not even a distribution that peaks at the two ends where there’s 1 ball and n-1 balls in the other….

Well, it’s not that counter-intuitive. Certainly, if you begin with exactly 1 ball in each urn, you end up with a uniform distribution on all outcomes, but the uniformity is kind of an artifact. In fact, the proportion of total balls in one designated urn is a martingale process, which means the proportion of balls at any number of times steps later is expected to be the same as the starting proportion. So, if you do not start with an equal number of balls in the two urns, there is no way that the long-run outcome will be uniformly distributed across the possibilities because that would give a mean proportion value of 1/2.

Furthermore, this means that indeed there is a rich getting richer “kind of thing” going on, if you deviate from equal proportion by chance. This is a weak effect that happens when the balls are few, but it doesn’t mean that the half-half case is somehow a counter-intuitive stable system. The paths that deviate early will indeed tend to go to the rails. It’s just that there are so many central paths that you aren’t likely to deviate proportionally unless it happens early.

What’s more interesting is that there are so many central paths. If you began with 2 and 2 balls, or 10 and 10 balls, you don’t get uniform outcomes, but a centrally peaked distribution around equal proportions. Indeed, if the number of balls is large, then addition of balls to urns one at a time doesn’t even move the drawing probabilities given by existing balls, and so it is reasonable to expect something like the central limit theorem to kick in.

So this is a case of deviation instability fighting with central tendencies of large numbers. To see this, keep the total number of balls the same, and move balls from the urn not chosen to the urn chosen, instead of adding balls to the urn chosen (and hence remove the latter cause from the “fight”), then it will clearly go to the rails.

scary sound effect

What exactly makes “scary” sound effects “scary”? By that I mean, what characteristics do they possess? A typical one is a high pitched, reverberated dissonant chord played on strings in certain films. Dissonance is a given, being in opposition to consonance that is often characterized as “pleasing.” But not all dissonant sounds are scary. Most are merely unpleasant, and one may even learn to enjoy them. It isn’t mental association, either, since certain sounds are intrinsically “scary,” without having been heard before. So what is it?

My best guess is, these sounds may recall the vocalization of some kind of open-range nocturnal predator of humankind’s ancestor, something one is innately equipped to recognize and fear.

Scientists create three-parent embryos

mitocondrial DNA from one egg, and a nucleus from another fertilized egg.

That’s going to screw up genetic testing and genealogical studies, for sure.

the sixteenth amendment not properly ratified?

A lot of people seem to write about that, claiming procedural error. That’s not what I care about, actually.

I am interested to know why people in the late 19th century clamored for an income tax. It seems strange. It looks like the farm lobby in the West at that time wanted a graduated tax to redistribute income, so I can understand some states being for an income tax, but three-quarters of the states? It seems difficult even to raise tax rates today, so where were the “tax protestors” back then?