Monday, December 21, 2009

Second Anniversary of Surgery

It's been exactly two years since my AP resection surgery. Last week I talked with Dr. A about my recent CT and MRI scans which show nothing new (yeah!). I asked what she used as the "zero time" of the survival curves - she said surgery date is something they use traditionally rather than diagnosis date. So I'm officially two years down the curve - these curves are called DFS-Kaplan-Meier(KM) probability curves (see graph below).

In earlier stages of cancer, these curves seem to have an asymptote - that is they flatten out to some non-zero constant (the number still surviving after x months). More likely, they approach the KM curves non-cancer people of similar age. Probably the slope is something like 1% per year. Compared to 30% per year (in the early parts of the Stage 3 curve), I'll take 1% as close to zero. :)

The winter solstice occurs when Earth's spin axis has it's maximum tilt away from the sun. This year, it occured today at 17:47 UTC. The spin access of Earth does not visibly change direction over a sinlge orbit of the sun. Due to the fairly even mass distribution, and damping forces, the earth's axis wobbles only slightly (and precesses slowly) - this is called nutation.

The solstice happens twice each year - in summer and winter. At these times, the sun's declination angle is an extremal - it "stands still" (sol stitum) as it changes direction from it's lowest or highest angle relative to the horizon. Of course, in the heliocentric reference frame, the sun stands still and everything else moves. This is pretty natural for our neighborhood. Relative to the galactic center of mass, the sun does move but at only about 250 km/sec (tiny by galaxy standards).

Thursday, December 17, 2009

Funny Stuff - Palin vs. Silverman

I'm in a light mood today. It's probably due to the unseasonably cold weather we are having today - bright skies and -10C. I'll post the more serious stuff next week.
Here's a picture I found of Sarah Palin - gosh I'm wondering why I did not vote for her.
Also, check out this video by another, smarter and funnier (and cuter) Sarah.

Utility Pole Replacement in Cambridge (Riverside)

Last night a wooden  utility pole  cracked at the base and fell toward the neighboring pole across the street. This caused the wires to d...